Last night drove to my RV parking lot and saw 2 leaky spots on the asphalt under the rv. Spot number one is in front of engine and spot number 2 is right under the torque converter.I have put a bucket to try to collect something which was a few drops of a red color liquid which my its look and smell looks like coolant.Radiator, and hoses are all dry. Seems that the leak could be in the front and go slowly to back of engine.Note that there is no leak if the engine is running and only does this when it cools down.Apparently there is a known problem on all Vortec engines doing exactly that, leak when cooling down and that the leak is the from part of the manifold intake gaskets.Anybody had this issue? Or any ideas?

Look closely from under the rig at the water pump vent hole. You may only see a small rust track.

The 5.7 Vortec were prone to leaking from the coolant passages between the lower intake manifold and the heads. Cause was reduced number of bolts that held the intake to the head (not the fact that it is DexCool). I had a small block so I'm familiar with them, I never got real familiar with the 454 since I didn't have one.The remedy was to replace the intake manifold gaskets and use an RTV called 'The Right Stuff' or 'The Good Stuff', I can't remember which. It is a black sealant in a pressurized can. Can be bought at Autozone/Oriellys and similar places.I had the leak on my '97 GMC. I had to replace a head at 207k mi and the above is what I used. My leak had never returned at 244k when I sold the truck.

Most likely it's the intake gasket leaking. Not a hard fix and it is a common issue. Put in the Felpro gaskets and torque down the bolts slowly and evenly. Do not over tighten use the torque spec and a torque wrench. I've done a lot of these. My own RV with the 454 Vortec went bad at 30K miles. Dave

Any idea how much time my Chevy dealership should be taking for such a job?Thanks

I've fixed 3 of these. They were all leaking on the right front corner of the intake gasket. (Passenger side). Fluids seek their own level. So the coolant level inside the radiator should be at the same level as the leaking area. They tend to leak when cooling down. I guess the heat expands and tightens everything up.A upper gasket kit used to be in the $100 range. The hard part of the job is pulling and getting the distributor back in the right spot. I could probably do one on a pickup in days time. A MH, I have no idea. I would think a shop could do it in a day but they always have scheduling problems and other things to work on. So I'd figure on at least 3 days in the shop.

7.4 Vortec coolant leak | Good Sam Community

DUNEBUGGYDOUG
Explorer
Sep 19, 2013
Pour in some Bar's Leak and keep on trucking
C350amg
Explorer
Sep 19, 2013
While we are down there should we not change the water pump, injectors and injector pressure regulator? I have 110,000 miles +
C350amg
Explorer
Sep 19, 2013
Peg Leg wrote:
I've fixed 3 of these. They were all leaking on the right front corner of the intake gasket. (Passenger side). Fluids seek their own level. So the coolant level inside the radiator should be at the same level as the leaking area. They tend to leak when cooling down. I guess the heat expands and tightens everything up.

A upper gasket kit used to be in the $100 range. The hard part of the job is pulling and getting the distributor back in the right spot. I could probably do one on a pickup in days time. A MH, I have no idea. I would think a shop could do it in a day but they always have scheduling problems and other things to work on. So I'd figure on at least 3 days in the shop.

Was afraid of the time it will take....
Peg_Leg
Explorer
Sep 19, 2013
I've fixed 3 of these. They were all leaking on the right front corner of the intake gasket. (Passenger side). Fluids seek their own level. So the coolant level inside the radiator should be at the same level as the leaking area. They tend to leak when cooling down. I guess the heat expands and tightens everything up.

A upper gasket kit used to be in the $100 range. The hard part of the job is pulling and getting the distributor back in the right spot. I could probably do one on a pickup in days time. A MH, I have no idea. I would think a shop could do it in a day but they always have scheduling problems and other things to work on. So I'd figure on at least 3 days in the shop.
C350amg
Explorer
Sep 19, 2013
Any idea how much time my Chevy dealership should be taking for such a job?

Thanks
The_Northern_Bu
Explorer
Sep 19, 2013
Most likely it's the intake gasket leaking. Not a hard fix and it is a common issue. Put in the Felpro gaskets and torque down the bolts slowly and evenly. Do not over tighten use the torque spec and a torque wrench. I've done a lot of these. My own RV with the 454 Vortec went bad at 30K miles.

Dave
boogie_4wheel
Explorer
Sep 19, 2013
The 5.7 Vortec were prone to leaking from the coolant passages between the lower intake manifold and the heads. Cause was reduced number of bolts that held the intake to the head (not the fact that it is DexCool). I had a small block so I'm familiar with them, I never got real familiar with the 454 since I didn't have one.

The remedy was to replace the intake manifold gaskets and use an RTV called 'The Right Stuff' or 'The Good Stuff', I can't remember which. It is a black sealant in a pressurized can. Can be bought at Autozone/Oriellys and similar places.

I had the leak on my '97 GMC. I had to replace a head at 207k mi and the above is what I used. My leak had never returned at 244k when I sold the truck.
enblethen
Nomad
Sep 19, 2013
Look closely from under the rig at the water pump vent hole. You may only see a small rust track.

Forum Discussion

7.4 Vortec coolant leak

About Motorhome Group

Related Content

Coolant leak

Coolant leak

Coolant leak

Coolant leak

5.7L Vortec vs. 5.3L Vortec