Sudden increase in blowby, shaking, no power, high egt, need help

[mpascino]

Quick history, the motor was freshened up around 15-20K ago. Valves were lapped, heads completely cleaned and checked. New rings, pistons, bearings, seals, Prechambers, chain, gears, Injection pump rebuilt, and injectors cleaned. Banks Turbo equipped.

Driving home from work today, notice an increase in the diesel smell along with a lite haze of smoke from the hood. I am only a couple blocks away so I continue home. Open the hood and see the oil fill cap is worn and is not making a tight seal. I fix the problem and think nothing more of it.

Head back out an hour later, all is well. Start to notice a lack in power on the high way and notice EGTs are higher than normal. I hit the gas a bit to keep up speed and realize that boost will not pull above 5-6 psi and the egts climb right up to 1100 in a couple seconds. I start wondering if my air filter is clogged up or if I tore the elbow going in the turbo again. I come to a light and now realize the truck is shaking like mad and see the smoke from the hood again except worse. I pull into a parking lot and remove the oil cap. The smoke from the crankcase quickly fills under the hood. The truck basically sounds like it is missing a cylinder, maybe two. I checked the air filter discover it is normal except for the excess of oil at the bottom(from the excessive blowby).

The truck starts fine, and does not seem to be knocking. Oil pressure is around 60 psi or so. The truck never runs above 150-160 coolant temperature and still runs cool. There are no bubbles in the coolant or water in the oil, everything appears to be holding pressure.

What could cause this so sudden? I find it hard to believe a ring or piston broken with only 15K on them. Could an injector or valve be stuck? Would that increase blow by? Unfortunatly I do not have a diesel compression tester nor do I know where to get an inexpensive one in a hurry. I don't think I can even remove the glow plugs or injectors in cylinders 4,6, & 8 with the turbo and down pipe in place. The truck is my daily driver which leaves me in a spot. Any advise and suggestions are greatly appreciated. Thanks,
Mike Pascino

[john8662]

It does sound kind of grim. A compression test will be the best tool to reveal whats going on. If you've got a cracked piston you could have the symptoms you're seeing. I just can't think of anything else it could be from an engine that's being driven regularly and this happening suddenly.

I've seen a nice compression tester set on ebay, and I've got one of them, it works great and hasn't given me any trouble (despite some other's opinions).

Here is one now on EBAY matco compression tester (http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&category=303&item=4392401334&rd=1&ssPageName=WDVW)

I have a few questions though, what brand components did you use for the build? Especially the brand of pistons you used, I've also been told that the 6.2L pistons really need to be coated to help withstand the heat from the higher combustion temperatures/pressure with the turbo.

[90LX]

What have you heard about the different piston brands? I'd like to hear some info as I may be rebuilding sometime.

[britannic]

Check your injectors and make sure they haven't started leaking and/or misfiring. Also recheck timing and eliminate any air leaks.

[mpascino]

Pistons were Clevit purchased from Northern Auto Parts, std bore. I pulled the glow plugs from the driver side and did not see any signs of oil and what not. I have to pull the down pipe before I can get to the other side. How can I check the injectors without replacing them. I was going to check the compression some how and then swap the injectors in any cylinder I found that has poor compression. Is it possible there is a dead spot in the injection pump? Thanks for the help guys.
Mike

[arveetek]

I don't believe you have an injector or valve problem, and I base this statement on the description you gave of the excessive blow-by. Unfortunately, the only way you're going to be getting that much blowby is by combustion gasses getting past the rings or pistons. A cracked block or head would give you oil or coolant problems. I would imagine you have a busted piston or perhaps some broken rings. Are you sure the rings were the proper size for this engine? Did you check piston ring end gap when assembling the engine?

A compression check is definitely in order.

I had a broken compression ring on my engine before rebuild, and I didn't even know it. My only symptoms were excessive smoke on startup, and a little smoke all the time after the engine was warm. I didn't have much blowby. That's why I suspect perhaps a broken piston.

Did you have the block deck resurfaced? If so, perhaps the pistons have been coming too far out past the deck. On a stock engine, the pistons will protrude out of the deck about .005". If you have the deck planed, they may take off up to .010". Then you might have piston/head clearance issues. Just a thought.

Sorry! :(

Casey

[mpascino]

Well the motor is disassembled in the truck now....#6 piston is cracked. There really is not any signs of heat damage although at the center of the piston it appears the temperature of combustion along with the pressure deformed blew a small piece of the piston aside. I will try to post pics later. The other three pistons look fine. The crack seems to have originated from a casting mark on the piston!! I have another set of injectors of the way just to be safe. I still need to find a place to buy 1 clevite piston to match the rest. My question is should I be worried about the pistons on the other side of the motor? The thought of pulling the other head off doesn't sound fun right now and I kind of need to get the truck going within the week since I will be moving shortly. All the cylinders on the driver side had 360-370 PSI cold compression. What do you think? Everything in the truck is new now for the most part. I just want to drive it for a year or so. I may be coming to terms that this thing is never going to come close to measuring up to a cummins..... I need to stop dumping money into it at some point....... I am going to install the TE06H turbo, so that should lower egts a bit more. Any advise is appricated.

[john8662]

I think you can get just one piston from Advance Auto parts or where you originally got your pistons from.

I think you could sure get away with the single cylinder overhaul in this situation.

The head gasket and head removal is up to you. I would rather have a matched set, and replace them both. But that is a lot more work, are you doing all this with the engine installed or on an engine stand?

[mpascino]

Engine is still installed, and like I mentioned earlier, there is only 10-12K on the rebuiild of the motor. Normally I would completely agree about the matched head set, but with my time constraints and bad back, leaning over the truck for another 4 hours doesn't seem adventagous. I hate doing stuff like this, however lately I seem to have better luck with "quick fixes" then any other way......I sourced a single piston from Car Quest. Advance only had the piston if I ordered online, which scares me a bit for a part like this. $40 for one piston.....I only paid about $140 for the whole set, I guess that explains my problem.

[arveetek]

Only $140 for a set of 8 pistons? I'm not sure where you got those, but most of the piston prices I came up with when I rebuilt my engine was around $50 a piston.

Perhaps that is a clue to why that piston failed....

Casey

[mpascino]

Ebay CAN be a good thing sometimes.....