I have a coolant leak on the back side of the engine. It is sometime a 12" puddle other times a couple of drips. I took it into the stealer and they said the backing plate is leaking. I do not understand the construction of these motors but this seems odd. Can anybody please shed some light on this for me?
Coolant leak back of engine
- Thread starter mechman3
- Start date
The rear cover of the motors is a removable aluminum "plate" (really a complex casting, but only 1-2" thick) that adapts it to either a SAE bellhousing pattern (Kodiak Medium-Duty trucks) or the standard GM V8 bellhousing (normal pickups). The coolant comes in the left side, and crosses over to the right side, entering both halves of the block.
The rear cover off my motor:
You can see the two big circular ports with o-rings that seal to the block.
And mounted on the motor, you can see the flat coolant crossover tube, and the blanking plate on the right of the motor:
That blanking plate is a common source of leaks. Well, not common, but more common than the ports that seal to the block.
The rear cover off my motor:
You can see the two big circular ports with o-rings that seal to the block.
And mounted on the motor, you can see the flat coolant crossover tube, and the blanking plate on the right of the motor:
That blanking plate is a common source of leaks. Well, not common, but more common than the ports that seal to the block.
Attachments
X2, if you have a EGR cooler or turbo coolant line leaking, it could just run down the back of the motor like that. Those coolant hoses are pretty old at this point, and having one just spring a leak at this age isn't unheard of.
So I thought I would post an update. The dealer I originally took this to will get a visit and an earful. They suggested that the coolant leak was from the backing plate crossover coolant line o-rings. They gave me an estimate of $1500. After the info given on this site and a shoutout to Mike L. I sought after a second opinion. Mike L was contacted because I want to build my transmission. I figured if the trans was coming out to fix the leak then maybe he could do it. Mike L looked into this and contacted a few people. They told him they had never seen a backing plate leak on a truck that was not torn apart. I finally took this in to a reputable local diesel shop. The verdict is a $300 fix to the turbo cooling line. DAVe3283 offered this as a possible issue and JoshH suggested looking up in that area as well.
Thank you all for your help. I now have $1200 more towards my transmission build!:coolspot:
Thank you all for your help. I now have $1200 more towards my transmission build!:coolspot:
I have a very similar issue with my 2006 3500 lbz. The shop that I took it to for a coolant leak on the drivers side back of the engine told me it was the head gasket. They tore the motor apart and replaced the head gaskets. The leak is still there. Now they said it was the backing plate O-rings and they would have to remove the cab of the truck in order to fix the leak. Is that really necessary? They might charge several thousand dollars to perform that kind of job. I will definitely get a second opinion for sure. This shop has had my truck for 65 days and it's been one excuse after another. The coolant leak is still there after being charged 4300 bucks. Thank you for the insight on this backing plate leak problem. You have really opened my eyes.
Lifting the cab is not needed to reseal rear cover. Pull trans and attack it from the back. Don't have to pull turbo or anything. Just lower pan, down pipe, up pipes and oil cooler elbow. Should cost under 2k