Coolant

[enforcer233]

Over the last month or so the low coolant light keeps coming on. I add coolant and it lasts a few hundred miles before I need to add more coolant. I do not see or smell coolant anywhere, no puddles under the truck, no coolant in the oil and no oil in the coolant? My truck is an 97 Suburban with 108,000 miles. Also the truck has never ran hot since I have had it. Even now it stays around the 185 mark.

Any ideas? I hope those of you who know do not say a cracked head, can not afford to fix that right now.

Thanks

[Hubert]

Look for a slow leak at the coolant crossover/thermostat housing quick connect for the heater. It can weep coolant so slow you might not see a puddle until it gets bad. It should start to build up a little pinkish crud though if its an appreciable leak. Try cleaning this area really good and watch for crud growth.

I THINK you can send off an oil sample and see if residue is getting in oil burning off then getting washed down by the oil in small quantities.

[Robyn]

Well you could have a slow leak that avaporates off of a hose or ???

Some slow leaks can be tricky to find.

An oil sample can be tested for signs of Glycol poisoning :eek:

Ethelyne Glycol will ruin bearings asap.

Get an oil sample tested.

The amount of coolant your talking would tend to show issue if it was leaking inside the engine.

Do this.
Start the rig cold or better yet have a helper do it and you sniff the exhaust right after it fires to see if you smell antifreeze.

Coolant leaking into a cylinder will burn off upon startup and will stink out the tail pipe.

Check the underside of your oil filler cap. If you see any water droplets or white goop this is not a good sign.

Does the rig have rear heat?? if so there could be a leak between the engine and the rear heater core.

Water pumps can seep as can any hose connection.

Look things over carefully especially when the rig is cold.

Cold leaks around hoses are common and will seep a little bit and then dry off and stop once the thing warms some.

Check the easy stuff first for seeps and leaks and if nothing is found get the oil tested for Glycol.

Keep us posted

[enforcer233]

OK Robyn, give me the bad news! I finally had an opportunity to look under the oil cap and there are small water droplets under the there. Head or head gasket?

[DmaxMaverick]

OK Robyn, give me the bad news! I finally had an opportunity to look under the oil cap and there are small water droplets under the there. Head or head gasket?

[I'm not Robyn, but I can wear the hat]

Answer: Either or both. Or worse. You'll have to get in there for a peek.

[enforcer233]

Thanks DMax. Not sure if I can handle worse or not. Time to find a wrench I guess. I'm sure I can get it apart to replace the head gasket, but I dont know how to check the head or how to recognize worse.

[Robyn]

The headas are not a 15 minute job to get off but doable in the chassis.

Drain all the coolant if you have not already.

Did you do this and run some clean oil through the beast??

Easy steps to get the thing apart.

Get the radiator schroud off as well as the fan Gives room to crawl in and sit while you work on the thing

Hood off is a nice perk too.

Unhook the battery cables.
Remove the manifolds and the turbo.
Remove the air plenum off the top of the intake.`
Remove intake manifold. (also little injector line clamp halves that will be obvious as you remove manifold bolts)

Mark the injector line pairs with a tag, tape or ?? and keep them in pairs.
1-3--- 5-7--- 2-4---6-8
remove the small retaining screws fron the line clamps at the valve cover brackets.

Remove the lines from the IP and the injectors. Cover the fittings on the IP outlets to keep crud out and do the same for the injectors.

A crow foot on a 3/8" breaker bar works real well to access the lines around the IP

Make a map of where the lines went on the IP as there are two that can be mixed up

#1 cylinder is LH front just like most GM V8's

You will find some fuel lines under and around the manifold too.
This stuff should be self explanatory (feed to the IP, drain line from the filter and the return lines)

The rubber return lines from the injectors can be severed at the line ends as you will be getting a new line kit anyway to reinstall things.

Now the Valve covers can come off. These are set using a real good silicone sealer. after the bolts are out use a thin putty knife to go around the edges and slide in between the head and the cover to free it up.

Dont reef on the covers or pry hard in one place as they will distort easily.

Once the covers are off the rockers can come off. Remove the bolts holding the two rocker shaft sets and lift the sets off.

NOW the pushrods on these engines are designed with one end that is hard Goes to the rocker and one that is not hard, goes to lifter.

The top end of the push rods are marked with a copper color on the ball end.

Some may be worn a lot but it should be evident.
Getting these back right is very important.

The head bolts are next. These are a one time though thing. The bolts must be replaced when changing the gaskets.
These are TTY (torque to yield)

$27 a set (per head)

There may be a ground strap on the back of the RH head so have a peek before you rip the head off and get it half way out of the engine bay :D

Once the heads are off stuff some clean rags into the lifter case area to keep crap out.

Likely the issue is going to be an end cylinder and not a center one.

With as severe a failure as you discribed it should be obvious.

Once you determine the cause you can set in motion the repairs.

If the rig was running good I might consider just a set of gaskets BUTTTTTTTT this would be a good time to consider all options.

We can go farther after you get it apart.

Keep us posted

Best

Missy Robyn

[HH]

How much water? Is it condensate or leaking? Make sure all your hoses are tight. I have had the light come on when the hoses were just slightly loose. I would do an oil sample (check for antifreeze) and/or a leak-down test first, before doing a major job like the head gasket, especially if you are unsure of where your coolant/antifreeze is disappearing to.

Just my $.02, the others are more knowledgeable than me.

[jasondmann]

Thanks for the great write up on how to change the head gasket! I will be changing mine in chassis in the next couple weeks. My truck seems to be running really good other than the bubbles in the coolant. Do you recommend changing anything else other than the gasket while I have it apart? I don't have a lot of extra money (so don't recommend injectors) but I've learned that it is cheaper to do it right the first time.

[enforcer233]

I am going to call my favorite wrench, a friend of mine, tomorrow about getting it checked first. I know that he has worked on 6.5's in the past in ambulances that my former fire department ran.

As far as the amount of droplets I guess to say it is condensate under the oil cap is appropriate.

I really do not have an appropriate place to work on the engine. Wen I said earlier that I could do the work, I could if I had a good place to do it. I do not have a garage, shop to work in, just have the truck parked along the street or in my back yard. Plus I would prefer someone who can test to determine which side is causing the problem do it.

One thing that stuck in my mind is that since I bought the truck in July 07, I had checked the fluid level by looking at the tank, but I had never taken the cap off, until the low coolant light came on, and I took it off to add coolant. When I took the cap off, it was not tight on the tank. It makes me think that the car dealer or previous owner knew a problem was coming, and had the pressure cap loose so the cooling system would not gain a lot pressure, forcing coolant somewhere it did not belong. I believe that it is too late to go back to them after 20 months. Kinda makes me feel stupid for not catching that sooner.

Live and learn. I will always remember to check under the oil cap in the future.

[enforcer233]

Well after almost a month I am getting the burb back tomorrow. When I called the wrench that I have used for years on my previous gassers, his reply was I really have no interest in getting into that (diesel engine work). When I asked who he thought I should I should take it to he replied take it to *&$%(## Chevrolet.

Not really feeling like getting raped be the local Chevrolet dealer shop. I spent a couple of weeks looking for a reliable diesel mechanic. I finally called a man who works for a local municipalipality as a mechanic who rus a shop on the side and has a good repitation. After getting the burb towed to his shop almost two weeks ago he called yesterday to advise that she was ready. He asked if I want the good news or the bad news first, I assumed the worst (replace engine, crank was bad, pistons ruined). The bad news, according to him was the price. But this was good news to me becasue it was around half what I expected. The good news was that it was finished and ready for pickup. He confirmed that the head gasket was the problem and that the head had been magnafluxed, milled and was in good shape.

One thing I learned from this experience that I want to pass on. Apparently the full synthetic oil I had been using, Mobil 1 Turbo Diesel Truck, does not get milky like dino oil when mixed with cooant water. So if you are using full synthetic and suspect a head gasket leak do not use this as an indicator of coolant in the oil. I also suspect that this may have helped save my crank and pistons from further damage.

Thanks Robyn and others for your advise and help.