View Full Version : Blown Head Gasket ? Cracked head ?
Truck has been running with a bit of vibration in it for the last few weeks. Until yesterday.
Towing the boat on the hwy, for one last river cruise. Motor starts REALLY vibrating, and losing power.
Pull over, pop the hood. Motor is rockin' at idle. Smokin pretty good, too, light gray, white, smells like unburned fuel. Maybe a very little blue, if any.
May smell a little like coolant, too, but not heavy. Hard to tell with all that fuel.
Will smoke black if I really step on it, but it's always done that.
Big whooshing sound coming out of the tail pipe, sounds like it might be only 1 cyl, but ?
No knocking, or other bad noises, whatsoever.
Limped home on side roads.
Not using oil, but I'm seeing little flecks or bubbles (coolant?) on the dipstick. Not the chocolate milk I've seen on major or long-term oil-water problems.
Coolant has dropped in the overflow tank, but a hose is leaking at a plastic tee, dripping on passenger side valve cover, intake, and off the rear of the head. This initially led me to think head gasket or cracked head, bad enough to leak out. Have not seen oil in the coolant, YET, cuz coolant level is too low.
So: How do I proceed to diagnose this ? And evaluate if I can afford to repair ?
Is it even possible to change a head gasket with motor in the truck ? I'm assuming it's the turbo side.
at 213k miles, I figure I also need an IP(original replaced at 25k), cam chain, water pump, harmonic dampener (first one failed at 125k, so I must be due again)
Anyone who's been down this road, please chime in.
john8662
10-12-2009, 12:32
Takes a compression test to tell for sure, that will point which cylinder has the gasket gone. This is also usefull when things do get taken apart, that way when you find the failed gasket, you can be certain that was the problem. You'll also need to do both head gaskets, but that's budjet dependent.
Pretty common.
I'd start looking for a set of reman cylinder heads (yours need rebuilding, and chances are they're cracked, just be ahead), and a gear drive timing set. This way you can get the parts yourself and save the cost of markup the mechanic is going to charge you for finding the parts.
It probably wasn't the balancer you replaced at 125k, but the damper pulley on the front, be good to inspect both as they will both be off for the timing set.
Otherwise... Replace the engine.
J
If the coolant level is dropping, is the oil level rising??
If the oil is contaminated then I would just yank the engine and get it out where you can get at everything.
Yank the heads, the pan and then you can get a better look at things.
At 200+K miles this little creature needs some lovin
I would not even look at reman heads for a 6.5.
Clearwater offers a new set of heads for $670 to the door and will pay the freight back on your junkers.
The clearwater heads use new castings and in many cases they refurbish the valves and use the rest of the good parts.
These heads are second to none in my opinion.
I have a set on the Burb with 40K now and doing fine.
With the high miles the bearings are likely on the way south.
The timing chain is toast, the sprockets will likely be fine with a fresh chain. (my 94 burb with 230K got a fresh chain is all)
Rings will probably be used up.
Tear it down and look the block over for cracks in the main webs as well as other issues.
The wrist pin bushings will be worn fairly well at these miles too.
If the sucker has ingested Glycol into the oil, the lifters will be contaminated.
A set of remans are $68 and as long as the cam is good (usually are) the new lifters will do fine.
Check the block over well for cracks in the main webs, lower cylinder area as well as a crack in the number 8 bore near the top.
Very possibly just a blown number 1 or 2 head gasket.
The block can be decked .010" or if you use Cometic gaskets you can go more.
My DaHoooley ended up being decked on one side .030"
Once the oil has been contaminated with glycol the stuff goes after the bearings quickly.
Keep us posted
Been through this game once back in 2005 with the Burb and again this summer on DaHooooley
Missy
Thanks, John and Robyn, your experience is well-appreciated.
Yes, John, it was the damper pully I replaced.
I don't believe the oil level has gone up. I just changed it 1k miles ago, and it's still at the full mark. First time I've used Shell Rotella T fossil, instead of Amsoil.
But something doesn't look just quite right. No milky bubbles on the dipstick, nothing under the oil fill cap. Just a few very very fine bubbles, almost like soot particles on the dipstick.
And oil further up the stick than I seem to remember seeing.
Is it possible to be blowing the fuel-air charge into the oil ? I could not smell diesel on the stick.
Didn't see any bubbles in the coolant tank after I re-filled, and ran in the driveway for 20 minutes. (smoked up the neighborhood, real fast !!)
I did hear a noticeable ringing coming up the oil fill tube, when checking under the cap. I imagine that's the loose chain....
I'm also guessing that increased pressure in the coolant could cause this hose connection to start leaking ?
Now, could there be anything else, besides a head gasket, that could cause the smoking and shaking ? As I said, there's no knocking or ticking. Valves stuck open ?
No CEL, no codes.
This burb has led a pretty easy life, tow 3000 lbs 4/5 times a year. Mostly highway miles at 70, never overheated even once.
Going out to buy a car tomorrow. Then I'll clear out the garage, tear it down, and figure out how to proceed.
If you remove the oil fill tube, does it HUFF out the hole when its
running. This would be a hole in a piston.
If no extra blow by then its gotta be elsewhere.
Be careful once the thing sits as a blown head gasket will allow coolant to fill a cylinder. Cranking will cause a hydro lock and it will snap the starter bolts off and knock teeth of the ring gear.
ASK ME HOW I KNOW THIS :eek:
The thing goes Clunk thud and then the starter falls off on the torsion bar.
Its a sickening feeling and costs a set of starter bolts, a ring gear and if you really hit the jackpot it can break the corner of the block off where the outer starter bolt goes in.
GAME OVER without some serious surgery.
Yank it out and get it open for an autopsy.
Save what you can and then let it rise like a phoenix from the ashes.
Keep us posted
Missy
john8662
10-12-2009, 18:51
From reading your last post it seems you'll be doing the work yourself, this will help stretch your budget tremendously.
The chain noise is normal, it's just the sound they make with a timing chain in them, still much the same even with a gear set. I think it sounds cool.
There are some shops selling reman heads that have been crack checked etc. to use. I know Robyn has been recommending the clearwater heads, but the jury is really still out on these as they're all cast in China. With only 40k miles on an engine with them on it, and not having seen how they're holding up, it's all unknown. With that said, the aftermarket heads could be made good use of if the casting is done good. The largest issue I've seen with them is:
1) Porosity. leading to coolant leaks in the cylinder. With that said, even a stock head could have this happen, but this seems to be more of an issue with the aftermarket heads.
2) Pre-cups. The pre-combustion cups in the cylinder heads of these engine see extreme operating characteristics, and the factory ones are made of stainless stee. The aftermarket cups that come in the heads are not up to this quality. A point to be made here is that if the stainless cups serve well but suffer some slight cracking, how well are the aftermarket ones going to hold out? Not well.
3) Machining. In relation to the precups mentioned above, you should not machine a head with the cups installed in the head, as this leaves the cups at a zero deck in the head. The cups need to protrude from the head .001" - .002" this is to help the gasket properly seat and keep the cup pinned in the head. Otherwise the cups can chatter in the head, which can potentially degrade the gasket's performance. Or even worse, have it sink ever so slightly.
Compromise? Perhaps take one of the aftermarket finished heads (with the reman used GM valves) and install some real precups at the correct depths.
All the aftermarket heads (including clearwater) that I've looked at all had the mentioned flaws. Just informing...
But, they're cheap.
I'd invest in a good compression tester, or Harbor Freight Diesel tester to test the compression before even tearing apart anything. This will save you so much "what if it's this" type of questions. Once you know where the problem is, you can tear it down knowing to look at the specifics surrounding that cylinder.
It's most likely a head gasket, they almost always fail on the ends. Cylinders 1, 2, 7, 8.
I wouldn't just pull the engine out and poke around at everything unless you're prepared to buy a replacement. One thing always leads to another. Fix what's wounded, enjoy the service you get from it.
jerry598
10-20-2009, 22:19
Right about the precups in the Clearwater heads. In the ones I installed the precups were machined flat with the head surface and did not protrude at all. In fact it almost looked like the precup ports were simply machined into the head and there was no precup at all. Does make me wonder.
All right now. Borrowed a Harbor Freight Compression tester, unused, from my buddy who is into mid-80's diesel Benz's. He never used it, because he never needs to. Imagine that.
Once I get one more project outta the garage, I'll start diagnosing the Burb. Being outta work, I cannot spend 1,2,3k rebuilding a vehicle worth 2-3k. About all I can do is new gaskets and a timing chain, IF the rest of the motor seems good enough to proceed.
This is not my preferred approach, I would much rather go the whole 9 yards, hoping to keep her forever.
I'm thinking what I need is some pass/fail compression numbers, above which I can consider diving in. Also, what are poor, fair, good and great numbers ?
Looking forward, and assuming positive results, I imagine removing exhaust manifolds from the heads might be troublesome ? Hints/tips ?
Thanks in advance. Kevin
With all the glow plugs out and tester connected.
4-6 puffs on each cylinder
360 is on the low end and 420 is great
Any wild swings (Low) indicates issues.
Even cyl pressure is what your looking for.
Keep us posted
Robyn
Compression testing.
This Harbor Freight set has a very short (1 1/8") glow plug adapter for our motors.
This works for 3 glow plug holes on the driver's side.
Does not work for any holes on passenger side. Not long enough.
I believe I need an adapter about 4 1/2" long, 10x1.25 thread, rigid. Must extend far enough to clear the tubes, shields, and get nipple past the exhaust manifold, so the quick release will seat.
What does everyone else use ?
Driver's side results looking good. All glow plugs on this side look good.
Front-to-back, 6 turns. 400, 380, 410, 300 until quick-release blew off, cant seat properly against exhaust manifold. But it was coming up the same as the other cyls, so I'm assuming it's about the same. The 380 cyl, adaptor may not have been torqued down as good as others.
Pass side.
Front-to-back. glow plugs: good, good,
third plug: noticeable white deposits, somewhat swollen.
rearmost plug : outside black with oil, element black, probably never glows due to oil on the wire. There's a long-term oil leak back here.
john8662
11-02-2009, 15:00
http://www.matcotools.com/Catalog/toolcatalog.jsp?cattype=T&cat=2318
You might look in your local phone book for your Matco rep and see if they can get you just the gauge and the one adapter you need.
I have the kit in the red case pictured on the URL above and it's a very good and accurate gauge. It's actually BETTER than the Snap-On gauge because of the increments on the gauge (more accurate).
Their adapter is perfect for fitting in and getting the measurement.
On the turbo side you'll have the best luck removing the rubber/felt shield in the inner fender to grant you access to the side of the exhaust manifold. You'll then remove the glow plug heat shields and wires (spray liberally with WD-40 prior to removal, connectors and all). After removing the wiring and shields for cylinders 4 & 6 you can then remove the plug, and use your adapter and connect the gauge.
That Harbor freight kit is a joke, well, you get what you pay for... The adapters won't be compatible between makes, so you need to get a gauge that fits your adapter, and vice versa.
Thanks, John.
That fender liner disappeared years ago, when I was going thru a starter a year ! Sitting around idling for long periods just baked them like taters.
Squirted everything two days ago, dropped the KD downpipe, and removed all plugs yesterday.
For some reason I didn't think to remove the heat shields around the plugs, but the adapter quick-couple probably won't clear the manifold, anyway.
Any members in Connecticut or Massachusettes have a compression tester I can borrow ?
I'll drive. What kind of beer you drink ?
#5 Note white deposits/swollen. Any thoughts ? Below and behind turbo.
#7 is black, probably never glows due to oil on connector. Or cylinder not firing. Thoughts ?
DmaxMaverick
11-02-2009, 22:54
Are you sure they were 5 and 7? 6 and 8 are under the turbo. The right/rear plugs usually come out looking the worst, nearly every time on a truck that doesn't have a known history. The reason has nothing to do with how that cylinder works, but the location does. Many, if not most, shops replace only 6 or 7 plugs. They lose too much time on #8 for a flat rate job. So, they don't and say they did. These engines start fine with only 5 or 6 good plugs, even down to all but the coldest of cold starts. By the time it gets that cold, the poor starting is usually blamed on the weather, fuel, or the boogie man.
The oil on the connector probably wasn't a factor with the plug. If the connector was snug, it got juice.
Yah, #8 has probably never been replaced. Maybe #6, too. So long ago I didn't remember....... what were we talking about ? LOL
Yes, I mixed up the numbering. Last time I worked on Dad's Expedition, it was numbered the other way.
Well, the Harbor Freight tester didn't work out. Incorrect adapter, inconsistent results. Borrowed a Snap-on set from a local shop that maintains a schoolbus fleet.
One of their mechanics mentioned valve train problems causing symptoms similar to head gasket - huffing sound back through intake, running rough, smoke, no bad mechanical noises. Says problem may be as simple as those plastic buttons, or.... Showed me some new metal clips left over from a recent job.
I've been wondering why I am still hearing a huffing sound, with all glow plugs out ?
(seems the same as when they were in)
I've been reading alot about bent pushrods, valve seals gone, lifters stuck and ruined....
How about a little advice on pulling the valve cover, and what to look for, in what order, once I complete the compression test.
If you are hearing noise from the intake manifold then you may have a collapsed lifter, stuck open valve or ??
Need to get compression on the RH side.
If you can't get thr tester in, try this trick.
Screw in the front plug on the RH side (all others out)
Roll the engine and see if it "Humps" good as it comes up on compression
If all seems ok remove that plug and go to the second hole on RH side
Repeat process until you do all of them.
You will likely find a dead hole.
A bad valve or collapsed lifter will show up as a hole with little air in it and the engine will not slow down much as it rolls through.
Keep us posted
Missy
Well, that was easy.
Just needed to borrow the right tools, in return for a 12-pack of Sammy's.
Correct glow plug adapter, joined to 12" of hydraulic hose and quick-coupling, then coupling to 12" of hose, to gauge. No wrenches/ratchets necessary, just twist the hose !
Sweet ! And, it bends around corners, steering shafts, manifolds, and fender wells !
OK, cranked 8 turns for each test:
#1 320
#2 310
#3 300
#4 300
#5 320
#6 300
#7 320
#8 0
I'm assuming the low-but-consistent values are OK, and are probably due to the large volume of hydraulic hose to be filled. There is no Schrader valve built into this adaptor.
I did see some numbers in the 375/380 range using another adaptor.
Put the glow plugs back in (except guess-which-one), and it started right up. Smoked up my neighbor's brand-new Camaro pretty good, so he took it home right away, before the smoke ate the paint off, and smelled up the interior !
Well, finally got down to it. Looks like flying carbon from intake valve got caught between the exhaust valve and seat. Are valves manufactured from multiple pieces ? sure looks that way.
So, what causes all this carbon ? Global Warming ?
What is up with the little plastic ring that holds spring and collar on the valve stem, after keepers are removed ? I had that sick feeling you get, when you pull the trigger, and you just hear ..... click.
Gasket appears to be intact.
Any good advice on how to free up heavily rusted exhaust manifold studs, so I can get that manifold off ?
Cylinder looks to be in very good shape, no scoring whatsoever. Factory crosshatching still
very pronounced after 213k miles. However, very minor pitting in the dark shaded area, looks like where piston was stopped while sitting. Location bothered me, right next to water jacket.
Maybe a touch of water getting in, too. Is orange stain around carbon ring at top of cyl from water and carbon interacting ? The other cylinders don't have any orange.
Advice/diagnosis/suggestions are welcome.
The carbon is from the cylinder problem, not the other way around. I can't tell from the photos, but is the exhaust valve damaged?
Yes, exhaust valve is missing a chunk. Hopefully you can see it in the SmValves picture. Sorry about picture quality, it's from the phone in the camera.
Yes, exhaust valve is missing a chunk.
That's what "started" it. Typical burnt exhaust valve. what caused the burnt valve is another story. Usually has something to do with not seating properly but carbon wasn't likely the cause. Could be a lifter that doesn't bleed down properly or deposits on the valve stem. When you first noticed the roughness it was not seating properly. The escaping combustion gasses did it in.
Lifter for that valve was bee-yoo-tee-ful. Looked like new.
All intake valves are carboned up. Intake runners very oily. Too much air filter oil ?
Or blow-by ?
No deposits on any exhaust valve stems. A little wiggly in the seals.
Any more thoughts on cause of so much carbon in the cylinder ? Bad rings ?
Other causes of burnt valve ?
I thought I read somewhere that a sloppy timing chain could cause retarded timing, and higher EGT's ? Possible ? I'm just thinkin out loud. But other cylinders don't look like this one.
Don't buy the Harbor Freight OEM valve spring compressor. Had to hammer it back into shape for every valve, and hold the jaws on the spring with channel-locks.
Anybody have a serviceable exhaust valve ?
The intake system on a 1500 diesel will always be skunked up bad due to the EGR
The EGR dumps a lot of crap into the intake (soot) that mixes with the oil vapor pull over from crankcase blowby.
The combination makes a nasty GOOP that collects on the valves and intake runners.
The backside of the valves can get so bad that the stuff can get to be 1/4" thick.
If a huge chunk falls off it make loads of noise as the engine beats it up and blows it out.
I have seen thuis happen to an engine that has sat for a while and the stuff falls off and locks the engine up.
I have a couple heads that came off DaHoooley and should have some good valves.
What diameter head (Just to be sure)
Let me know and I can yank one out..
Missy
I captured the piccy of the #8 cyl wall and tweeked it a bit so I could get a better look at it.
Here is a pix back that I marked with an arrow pointing at what I se as the "suspicious area"
Is this the area with the Pitting and discoloration???
If you want you can email me a very high res LARGE file pic so I can get a better look at it.
cloudmt.ranch@bigborecanyon.com
What I see here if it is indeed what I think is the infamous number 8 cylinder crack.
The strange little mark in the cylinder is in the right location to be trouble.
Some blocks would crack in the rear area of the cylinder just below the deck and bolt bosses.
Get me a hig res piccy with lots of light and I will look it over well.
The small file size allowed here at the forum makes very fine details in a large size piccy very tough if not impossible.
If this indeed a cracked cyl wall the news is grim.
Not without a fix but not a quicky either.
The fixes could range from another block to sleaving that cylinder.
Lest have a closer look first.
The cracked cylinder syndrome also causes loss of coolant and pressure in the cooling system too.
Missy
Until I see a closer Piccy of the cylinder I can't be absolutely sure BUTTTTT
Here is my opinion at present as to what has happened.
The number 8 cylinder wall is cracked right opposite the large water passage.
The cylinder has been taking in small amounts of coolant and this combined with HOT valves may certainly have lead to the valve issue.
The engine has been in trouble for some time, the final issues with the valve was just what brought things to your attention.
I would recommend this course of action.
Clean that strange looking spot in the cylinder with Brake Kleen and a rag real good.
Lightly sand the discolored area well with 400 wet dry abrasive paper to get it clean.
Clean again with Brake Kleen.
GET a good close up High res Piccy.
Now you can either dye check the thing or you can soak it with tranny oil over night.
Raise the piston to just below the area in question, fill the area with tranny oil and let sit over night.
Now remove the tranny oil, clean the cylinder real good with a rag and then gently wipe the area in question off with a rag soaked with Brake Kleen.
Dont soak that area just get the surface clean quickly.
Get the piston back out of the way.
NOW heat that area with a small propane torch till its hot to the touch and let sit.
A crack will show a thin line of oil OOOZING out.
I do not recommend sleaving a 6.5 especially when this particular cylinder cracks.
Unfortunately this situation makes the whole scenario far bigger.
I realize you had hoped for a quick fix and back together.
Then head can probably be saved with a valve and a lap job on the seats along with a good cleaning and some fresh valve seals.
Personally I would start looking for a good block thats not cracked and that has good cylinders.
You can transfer all your parts to another block and be in good shape.
Rings, bearings, gaskets and a set of head bolts and you could be off to the rodeo.
If you are careful and keep everything in Order you could swap everything including bearings from one block to another.
A low budgit job could even just wash the rings up and reuse, BUTTTTT I would at least rering it.
I was involved with two cracked number 8 cylinders over the last few years.
One was sleaved and there were issues within a few months and the other one was scrapped right off and another block scrounged up.
Hummers were plagued with this problem, enough that there have been several write ups online about the issue.
The 97-99 blocks seem to be the worst for this issue.
You can use any older block with your engines innards.
Stay away from early 506 Blocks (97 production)
929, 599 castings are a good choice.
All is not lost. Just dented and its feelings hurt is all.
Missy
Looked the pics over that you emailed.
Looks very suspicious.
You need to do one of two things. Either dye check the thing or rig up a plate to bolt over the hole and pressure test that cylinder.
Fill the block up with water so that the fluid level is above the level of the bad spot and then put 90 PSI or above air pressure on that hole and see if it bubbles in the water jacket.
To keep coolant in the block screw bolts in the lower head bolt holes and use some Modeling clay or some such thing like strip caulk in a wad to plug the other coolant passsage holes.
This will allow you to get the liquid level high enough to see if there are any leaks
Keep us posted.
Missy
Will do. Sure appreciate the help. Will pick up some dye tomorrow.
Hared to raise such terrible news, but after reading all of the thread and digesting the part about the Pits and shadow spot stuck in my mind.
Just had to look that piccy over real good before I said anything.
That spot is right in the usual place that number 8 can crack.
Let us know what you find with the crack check dye.
Missy
jerry598
01-06-2010, 23:20
Slightly off subject Robyn, but - my machine shop bored out the cylinders in my 929 block to .040 oversize. Replacement pistons came marked on the box for that size. The Army 6.5 manual says that .030 is the max. allowed. Is it possible that boring out over the .030 limit to .040 lead to cylinder cracks?
If .030 is fine then another .010" is not going to cause issues.
GM even offered .040 pistons actually that would be 1mm OS
I wouls not be afraid of going 1mm OS on a 929 block.
The crack being dicussed in this thread is due to a stress riser that is present right under the head bolt Boss area on the number 8 cylinder.
I am not sure exactly why these crack but the 97-99 Hummers were real bad about it and the same engines in the late pickups and Burbs will also do it.
I have not had any of my personal engines do this but have been involved with two blocks that had failed in this way.
One block was bored out and sleaved and it had head bolt hole failure a few months later.
The holes cracked between the sleave and the bolt.
Now
Installing studs into the block to eleviate the spreading forces might have been enough to keep things intact.
The machine shop I use WILL NOT sleave a 6.5 due to several failures and the subsequent hard feelings that followed.
The Military has many things that may or may not make sense and the .030 max is just one of them.
I personally try to keep from boring any farther than need be just because.
I bored the DaHooooley at .020" (.5mm) for a couple reasons, 1 the pistons cost me $199 off ebay and 2 the rings were surplus Mil stuff that cost me $35 for a complete set.
The cost savings alone were very good.
Had this same deal presented itself for .75 or 1mm I would likely have done it that way.
I wanted a good engine and it needed to come at the cheapest price possible.
I would not worry at all about the 1mm OS bores.
Missy
The good news is #8 cyl is not cracked. But found another cracked exhaust valve.
Check out the pix of #2 gasket and head. Can see daylight between the seperated fire ring, (hard to see in the pix) and look how close the fire ring runs by the valve. after washing the head, there's some erosion right where the ring should have sat.
Just wondering if this was the factory install, or if dealer had to go in here while PO had the truck. I bought it 4 years old with only 11k miles on it.
Found out why the valve cover leaked, look at the machining on the head.
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