[GMC06EnvoyXL]

Hi all, need some reinforcement/direction. I have a 06 V8 Envoy that had the DOD lifter failure. I replaced the lifters with new ones on the passenger side and the truck runs great. After driving a few miles, the car will overheat and coolant will pour out the bottom of the truck. I can't tell where it's coming from because the whole engine area is covered with coolant. Also the oil pressure is dropping to 0 forcing me to shut the truck off. I have only had the truck a few months and only drove it 100 miles before the lifter failure. No issues before that.

I'm assuming I did something wrong when I replaced the lifters. My guess is that I didn't tighten the cylinder head enough (I had no degree gauge and was paranoid about breaking a bolt). I think that could cause my overheating issue. What about the oil pressure? Would a non-sealing head gasket cause oil pressure loss?

I'm tearing the motor apart again. Should I use copper spray on the head gaskets this time to be extra sure it will seal? I'm going to buy new bolts and a degree gauge this time. Anything else I should look for?

 

[GMC06EnvoyXL]

I should mention that the overheat, leak and oil pressure loss only appear after driving the car. Nothing when it's idling in the driveway for over 20 minutes.

 

[princej99]

I should mention that the overheat, leak and oil pressure loss only appear after driving the car. Nothing when it's idling in the driveway for over 20 minutes.

hi, welcome to the site.

the dod on demand system has been a real problem for these engines and other v8's.

I know its been mentioned before to do a dod delete kit if you can to avoid the failure in the future.

the symptoms you describe can be bad head gasket sealing. Is there coolant in the oil, oil in the coolant?

 

[GMC06EnvoyXL]

Thanks...I wish I would have viewed this site before buying the truck because I would have steered clear! The DOD is a pile for sure. I don't want to delete it because I'm avoiding taking the working drivers side head off. I did install a new oil distribution thing in the valley that is supposed to be engineered better.

I don't see any coolant in the oil, but it's hard to tell. If I run the car with the radiator cap off and the thermostat open (warmed up) and rev the engine to 2k, a lot of "burping" and bubbles show up in the radiator coolant. At first I thought I had air in the system, but now I'm thinking its the engine pressure pushing the coolant because of a bad seal.

Do you think I should put that copper gasket spray on the head gasket? If it looks OK, can I reuse the head gasket assuming the leak was just due to poor torque of the head bolts?

 

[princej99]

Thanks...I wish I would have viewed this site before buying the truck because I would have steered clear! The DOD is a pile for sure. I don't want to delete it because I'm avoiding taking the working drivers side head off. I did install a new oil distribution thing in the valley that is supposed to be engineered better.

I don't see any coolant in the oil, but it's hard to tell. If I run the car with the radiator cap off and the thermostat open (warmed up) and rev the engine to 2k, a lot of "burping" and bubbles show up in the radiator coolant. At first I thought I had air in the system, but now I'm thinking its the engine pressure pushing the coolant because of a bad seal.

Do you think I should put that copper gasket spray on the head gasket? If it looks OK, can I reuse the head gasket assuming the leak was just due to poor torque of the head bolts?

burping and bubbles, is usually a sign that engine pressure is pressurizing the cooling system.

I would prefer to use new head gaskets, but would defer any action until a forum member with more experience in the v8 engines is able to weigh in.

 

[atv hauler]

Thanks...I wish I would have viewed this site before buying the truck because I would have steered clear! The DOD is a pile for sure. I don't want to delete it because I'm avoiding taking the working drivers side head off. I did install a new oil distribution thing in the valley that is supposed to be engineered better.

I don't see any coolant in the oil, but it's hard to tell. If I run the car with the radiator cap off and the thermostat open (warmed up) and rev the engine to 2k, a lot of "burping" and bubbles show up in the radiator coolant. At first I thought I had air in the system, but now I'm thinking its the engine pressure pushing the coolant because of a bad seal.

Do you think I should put that copper gasket spray on the head gasket? If it looks OK, can I reuse the head gasket assuming the leak was just due to poor torque of the head bolts?

No,do not reuse the head gasket or bolts.The gasket should be installed dry. Also make the bolt holes have no coolant in them before install.

 

[GMC06EnvoyXL]

Thanks guys, new head gasket and bolts are on the way. I tore the engine down to the head and found a coolant hose that had a questionable clamp. I suppose that the hose would not leak at idle, but while driving would dump coolant out enough to the point the car would overheat.

The bubbles in the radiator were not constant, but I'm sure would get worse if I left it the way it is. I noticed the slightest cream color on the oil filler cap. Not even noticeable until you wipe it away.

I'm going to see if Autozone has a torque angle gauge so I know that I turned the bolt the right amount of degrees instead of eyeballing it. Those bolts are a pain to tighten in the truck! I have a pipe to use, but of course it is a little long and hits the hood prop or some other area of the truck!

What about the low oil pressure issue? I have read others have a similar issue with no real solutions. I didn't have any problems until I took the head off. Maybe it is coolant thinning the oil? Hopefully the new head gasket will seal and this problem will go away as well.

 

[princej99]

Thanks guys, new head gasket and bolts are on the way. I tore the engine down to the head and found a coolant hose that had a questionable clamp. I suppose that the hose would not leak at idle, but while driving would dump coolant out enough to the point the car would overheat.

The bubbles in the radiator were not constant, but I'm sure would get worse if I left it the way it is. I noticed the slightest cream color on the oil filler cap. Not even noticeable until you wipe it away.

I'm going to see if Autozone has a torque angle gauge so I know that I turned the bolt the right amount of degrees instead of eyeballing it. Those bolts are a pain to tighten in the truck! I have a pipe to use, but of course it is a little long and hits the hood prop or some other area of the truck!

What about the low oil pressure issue? I have read others have a similar issue with no real solutions. I didn't have any problems until I took the head off. Maybe it is coolant thinning the oil? Hopefully the new head gasket will seal and this problem will go away as well.

we hope the low oil pressure will go away upon completion of the new head gasket.

please update this thread. and pics of the removed head would be nice.

 

[atv hauler]

Thanks guys, new head gasket and bolts are on the way. I tore the engine down to the head and found a coolant hose that had a questionable clamp. I suppose that the hose would not leak at idle, but while driving would dump coolant out enough to the point the car would overheat.

The bubbles in the radiator were not constant, but I'm sure would get worse if I left it the way it is. I noticed the slightest cream color on the oil filler cap. Not even noticeable until you wipe it away.

I'm going to see if Autozone has a torque angle gauge so I know that I turned the bolt the right amount of degrees instead of eyeballing it. Those bolts are a pain to tighten in the truck! I have a pipe to use, but of course it is a little long and hits the hood prop or some other area of the truck!

What about the low oil pressure issue? I have read others have a similar issue with no real solutions. I didn't have any problems until I took the head off. Maybe it is coolant thinning the oil? Hopefully the new head gasket will seal and this problem will go away as well.

Your oil pressure might be ok. It could be the screen under the oil pressure sender. Since you have your intake off, the sender/sensor is at the back of the block.This screen is used on the DOD engines and can been plugged with
debris or white oil/coolant pudding. You can use ARP head bolts which you torque instead angle/degree method.

 

[GMC06EnvoyXL]

Man I wish I knew there were torque bolts available instead of torque to yield. I already ordered the latter so I guess I'm stuck using those. I thought about the screen issue, but isn't it part of the DoD valley cover? If so, I have installed a new one.

When I removed the intake I noted a little oil on the valley cover. You can see it in the pics. Not sure if that is normal or not. When I removed the head, there was some antifreeze in the very bottom bolt holes in the middle. I assume that is normal?

Here are pics of the head:

 

[GMC06EnvoyXL]

Update: I finally got the car put back together. The torque angle gauge worked OK and I also followed a suggestion I read to put a dab of nail polish on the head of the bolt so you can see how far it turned. I'm glad I did that because the angle gauge failed to register my degrees once and the nail polish saved me.

It seems that at least part of the problem was the head gasket because the oil I drained looked milky.

The car started fine and oil pressure was over 40 psi at idle. I ran it for a few minutes until I saw smoke coming from the passenger side of the engine. I'm hoping it is from the oil I spilled trying to fill the engine. I did not notice any leaks so that's a good sign.

The check engine light was on (it was on before because of the passenger side O2 sensor, not sure if related to my problems). I scanned it thinking I would get the same code but 9 popped up! I'll have to make sure I didn't forget to wire in a sensor, unless this is normal when the battery has been disconnected for a long time? I know my wife's Jetta will light up like a Christmas tree if the battery is dead for too long until you drive it around the block and everything "resets". Hopefully tomorrow I will have time to run it longer and see what happens.

 

[GMC06EnvoyXL]

Yesterday I let the car run with the radiator cap off and heat on. The antifreeze was bubbling and then a loud "burp" followed by the fluid level dropping. I topped it off a few times and the car never overheated.

Today I checked the antifreeze level and it was the same as yesterday so I took the car out for a test drive. Ended up going over 30 miles, at speeds ranging from 30 to 80 and the car never went past the middle of the gauge. Also the oil pressure never dipped below 40. Fingers crossed the head sealed and it's finally fixed!

 

[STSCowboy]

How long did it take to replace the lifters? Exactly how did your DoD fail?