HELP! Overheated everything--need some direction

[KenZ]

I need some guidance!! I'll try to make this short...but its a long story

I overheated my truck--transmission and engine. 2002 LB7 Duramax engine. Hauling my camper up a mountain, the tranny stuck in overdrive. (found out it had something to do with the anti lock brakes, and transmission was getting a signal not to lock up) It was late and only had about 5 miles to go to get to the campground, but they closed the gates at 10 so I pushed it up the mountain at 15mph on hairpin curves. Dark and nowhere to pull over and 3 daughters with me in the truck. Engine temp and transmission temp both pegged to the max.. Made it through the first campground gate, 3 miles to go. My daughter asked what it meant if the transmission temp gauge went to zero, I said that's not good. Something blew and truck lost power, coasted to the side, engine still running, then BAM!!! something else went, steam everywhere, I thought it was the radiator hose. Engine started to knock, so I shut her down.

What I found was when I lost power, it was two of the transmission lines that blew. Lost most of the transmission fluid. Then the loud explosion wasn't a hose, but the side of the radiator blew out. Had to get the truck towed 270 miles home.

I was thinking cracked head, blown head gasket, ruined transmission--big dollars. Truck has 207,000 miles, I use transynd in the tranny and Rotella synthetic in the engine. The transmission was so hot that the lines that burst had the internal reinforcing fibers melted and the transmission line holders were melted. Some plastic under the engine was melted.

Truck would still start after all this happened. but couldn't run for long with no coolant.

So I determined what I needed to order, but the injectors needed to be replaced anyway, So I ordered a set and set out to do that while waiting for the other parts, along with a new power steering pump, belts, hoses and other general maintenace.

Old injectors came out very easy with my fingers and a slight twisting. Everything was very clean under the valve covers. I was careful not to dislodge the steel cups. and none seemed to be loose. Put it all back together and waited for the radiator to come. Got that in and filled it up, primed the fuel lines and she started up and sounded great, but blowing the coolant back out of the overflow tube. I tried and tried to get it to stay in, but bubbles keep coming out. I was hoping that it was an air lock, but have had no success in getting the coolant to stay in the system.

She actually sounds great, much better than the old injectors, and I ran it down our long driveway a couple of times and she sounded great and the transmission was actually working. (pulled the pan and changed the fluid and filters, which really smelled burned, but the pan was clean, no junk in it) The truck is purring like a cat and sounds great--no misses, great power. Engine has never used any oil until over 10000 miles on an oil change, so I think the engine is in good condition.

So the injectors was an extra thing that needed to be done, but now back to the real problem. Did I crack a head, blow the head gasket, or is an injector cup leaking? It wouldn't be a crack in the block would (could) it?

It got really really hot. If I have to go back and take the valve covers off, it will go much quicker the second time, but I hate to have to pull the heads--especially both.

What would you do? Do I try to find which side the pressure leak is on--and what is the best way to do that. If I can identify a particular side or cylinder that may have lower compression, should I try to just re seal the injector cup, or go ahead and pull the head and have it checked and replace the head gasket. Can I do that with the engine in the truck. I know I have read the post about pulling the engine or lifting the cab, but I dread doing either of those things.

I even thought about trying to find a replacement engine--If I have to pull the engine, and I have seen some rebuilt long blocks around 4100.(One place in Norfolk, which is only a couple of hours from me) I really don't have that kind of money at the moment. If I have to replace the heads, I would probably get up to a couple thousand pretty quick. If only the head gaskets, still maybe $1000?

Where is the best-least expensive place to get the head gaskets and bolts if I have to go that route.

Any questions, let me know.

So which direction do I go--? Thanks in advance for your thoughts.


Ken

[Mark Rinker]

Sounds to me like you burned up your engine and transmission in exchange for a safe trip off the mountain at night.

I'd be looking a for a low mile LB7 takeout engine/transmission from a wreck, and save the new injectors to freshen up that one, before you install it.

As for the anti-lock brake system telling the transmission not to lock up? Check your sources...

[DmaxMaverick]

ABS errors won't cause any problems with anything but the ABS. At most, the ABS won't engage. Different problem. Don't relate this with your overheat issue.

In all likelihood, you were in "Limp Mode" when this began. Something caused limp mode (tranny or TC slip from too much power and load, such as using a power module/programmer, for example). This locks forward gears to 3rd (not OD), and limits engine RPM. If you are using a power mod, 2000 RPM's is more than enough to overpower the torque converter (which won't lock in Limp Mode), creating all the heat you saw. You need to pull the DTC's to determine the root cause of the issue.

That said, I don't think you've "blown" the engine or tranny to a point of replacement, just yet. Perhaps a head gasket, which wouldn't be surprising with what you've described. The radiator tank ruptured due to the excessive ATF heat, which also caused the ECT to overheat, before the coolant loss.

It can take quite a bit of time and running to get the coolant system completely bled of air. Once most of the air is static bled from the bleeder screw on the thermostat housing (fill the tank above that level and bleed until coolant runs out of the bleeder), the procedure requires the engine to be ran up to 3,000 RPM's (tranny in P) for several 10-20 second intervals, until the tank level stabilizes. 8-10 times, or more, wouldn't be uncommon. It's important to NOT let the tank level drop below the low level, or it will pull air back into the system between intervals. If once it's properly bled, you are still getting air bubbles at the reservoir, then you do have a combustion breach. You won't know exactly what it is until you get the heads off. Don't count on an injector cup. Due to the condition and excessive overheating issue, I would recommend replacing head gaskets, in any case. Later gaskets are much improved over your originals.

I suggest fixing what's broken (radiator, head gaskets, etc.) and see where you stand. If you have a cracked head, you'll see it once you get them off. If they were cast iron, the likelihood would be high. These aluminum heads are very resilient, by comparison, so don't cross that road just yet.

If you are doing all the work yourself, head gaskets can be done for a lot less than $1,000. It can be done in-frame if not using studs. A lot more difficult is using studs (but not impossible). I also suggest replacing the thermostats, due to time/mileage, and the overheat episode. Don't fill with Dex-Cool until you get it all sorted out. Use only distilled water. Once everything is finished and in good health (I'm optimistic), drain the water and add the necessary Dex-Cool, then top off with distilled water.

[Mark Rinker]

I am certain DMax has the best advice here. Hope you have a quick resolution to your problems.

My thought was based largely on the 200K+ miles already on the drivetrain. While there is probably another 200K of potential left, if you could find a takeout drivetrain with half the miles, it might be worth the expense.

Its a crapshoot either way...and I have crapped out some times, and I have walked away with a fistful of green, others! ;)

[KenZ]

Thanks DmaxMaverick.

The Allison service manager (not GM dealership) explained that a bad sensor would look like a skid condition and prevent the lock up in the transmission and then cause extra heat. The tranny situation had been going on for a while on and off and I had pulled some codes. It made sense the way everything was acting. It would go away for a couple of months and then come back. When I pulled the radiator, part of the culprit was a mat of weed seeds blocking the radiator on the inside where you can't see it. Between the intercooler and radiator. I do blow the radiator off and pressure wash it, but never between the two--so a warning to anyone driving out in tall grass! It was in the fins so tight, I couldn't blow them out after it was out of the truck.

So anyway apparrently there was a slight overheating of the transmission due to the radiator blockage, and the ABS code. And yes, it would get stuck either in 3rd or overdrive. I was in 3rd for part of the trip and pulled over to let it cool down. It went into overdrive-on the interstate and I was doing 70 and looked at the rpm's so I know it was in overdrive. Got of the interstate for the climb in the mountains and it wouldn't come out. Just got hotter and hotter from the slippage.

No mods on the truck at all.


I've tried bleeding and just can't seem to get all the air out. One time the bubbles did stop and I had hope, but I think the cap was balancing out the pressure. Seems that it must be a very small pressure leak. The top radiator hose gets hard shortly after I start it, if that is an indication of a pressure leak.

I did replace the tstats already. and bled from the thermostat housing and ran up to 3000 rpms several times. but maybe not for 20-30 seconds--so I can try that again. The problem is all the water comes out when I rev it up. If i leave the cap on, it blows less out, but enough to be low and I have to take the cap off to add more water and then as soon as the pressure is realsed, more water comes out. Seems like an endless cycle.

Would it help to remove the thermostats? Seems like they are holding the water back from going into the heater until they warm up. When they open I get a surge of hot air from the heater, but by now the low level comes on and back to the cycle again.

I'll try the bleedind one more time and them I guess I will start to tear her down. I was just hoping there was a way to locate which side and do that one side.

I'm really expecting it is a gasket, as it is running great except for this pressure in radiator problem.

Do you recommend the "C" gasket. I think I read on a post that JKennedy always used the thicker gasket. If I pull the heads, I will take them to a shop to have them checked and resurfaced if necessary and not too expensive.

Thanks for the input!

Ken

[DmaxMaverick]

I don't disagree with what you said earlier, Mark, necessarily. He's already into the needed repairs pretty far, both work and expense, and he's been under the valve covers before, successfully. The gaskets are only a couple hours more than what he's already done, if it comes to that. It's possible it just needed properly bled, although I think gaskets are on the short list.

Limp mode is just that. Limp mode. Driving any more than what is absolutely necessary, especially under extreme conditions (heavy load and steep grade), is pushing the emergency system beyond its design. It's like using "doughnut" spare tires full time. I know of someone who did that (on all 4, because he got them real cheap), and it caught up. It cost him a LOT more than what he saved by not buying tires.

[DmaxMaverick]

When bleeding, leave the cap "loose". Tightening will slow/prevent the process. You don't want pressure building until all the air is out. And, it does need to be up to temp, stat(s) open.

Having high pressure (hard hose) immediately after a start is not promising. No amount of bleeding will cure that. Try applying shop air to each cylinder (one at a time, through the GP hole) with the piston BDC, valves closed (combustion stroke), coolant cap off (watch for rise or bubbles), and oil fill cap OFF. You can use a compression test adapter, or a rubber-tipped nozzle. Any cylinder with a blown gasket or cup should stand out, immediately.

If you aren't decking the block, it doesn't really matter which gasket you use. If the block is decked, you MUST use the thicker gasket. This is true for every zero-clearance engine, gas or Diesel.

[KenZ]

Good idea on the pressure through the gp hole.

Couple of last questions and I guess I will be laboring on my truck during Labor day.

If I pull the heads, should I remove injectors again and seal cups, or leave them in the heads for the removal? I know its ultimately my decision. just wanted your opinions.

Do you have to surface the heads or what tolerance is allowable before I have to machine or replace?

Mark, I know what you are saying, but I know the history of my truck and how it has been maintained, so I feel it is good to go if I can take care of this issue. For some reason I don't want to have to pull the engine, even though some say it is no big deal. I really don't have a good place or shop to do that. I also did some quick looking around and couldn't find an inexpensive LB7 around here.

You guys are great with your quick responses. I'm getting more settled in my decision to replace the head gaskets.


Thanks!

[DmaxMaverick]

Normally, we shouldn't mess with injector cups without specific reason, like if they unseat during injector removal. However, unless you can verify the "overheat" condition didn't actually involve the heads, and the cups are still, in fact, sealed, I would reseal them. There will never be an easier time to do it than now, while you can work on a bench. It will eliminate the possibility they are a cause of a leak.

Unless you have a reason, the heads do not require any machine work. If they are true (within spec) with no indication of damage, they get cleaned up and go right back on. I don't normally mill aluminum heads, unless there is an indication of surface damage. Most shops and mechanics do, but it's essentially "old school" habit. Modern aluminum heads don't require it if the surface is not damaged. It would be surprising to see an aluminum head come off that didn't show some degree of warpage, even if they were either brand new or rebuilt, and ran for a week or a day. You have no way of knowing what it's doing under the stress of clamping (bolts), heat, and combustion punishment. Microscopically, they bounce around like ping-pong balls during use. At the same time, I don't weld combustion chambers, runners, jackets or valve seats/bridges. These are high performance engines (built to run on the ragged edge), and should be handled as such. I have yet to have one come back. DO NOT swap the heads, left-right.

As far as a replacement goes, a used engine will be just as likely to need the SAME repairs sooner or later you are looking at right now, on yours. Like you said, you know what you have, and have no idea the condition/history of another. Unless your shortblock is damaged, which seems doubtful at this time, you'll know more about it than any other option when you're done. And, it'll be a lot less expense and busted knuckles in the end.

[More Power]

Good advice Greg! I agree that discovering what's wrong should be the first step in the process. I've heard of heads warping, and this kind of heat would do that. The heads must be thoroughly checked out.

Unless the Duramax lifters are different now than those used in the LB7, they all use solid roller lifters with adjustable rockers.

Jim

[KenZ]

Ok, I got the heads off and have a question. There is an indentation in the head around the perimeter of the cylinder where the head gasket seals the cylinder,-- where the edge of the gasket has been pressed into the head. The edge seems a little thicker than the rest of the gasket and since the block has no give, I'm guessing it just pressed the gasket edge into the aluminum head. Is this normal? How much indentation is normal or allowable? Other than this I see no damage. I will take them and have them pressure checked, but if this "dent" is not normal, I don't want to spend an extra $110 to have them checked for no reason.

thanks again,

Ken

[KenZ]

two more questiions-- Does anyone know what type of gasket sealant is used to make the gasket on the intake manifold?

The gaskets on my heads were grade b on the drivers side and grade c on the passenger side. Since the passenger side is already the thickest gasket, Do I have any room to shave the head .003 and not have a problem? What is the normal valve clearance to the piston? (three questions).

Thanks!