Greetings all and Happy New Year!

I have a 1978 Delta 88, 4.3L, 260 cid V8.
Maybe 2000 miles on an engine rebuilt August-September 2011.
Transmission (TH350) rebuilt June/July 2011.

Noticed a puddle of coolant on top of the front of the engine block. This has happened about 2 or 3 times in the past month. I have refilled the overflow tank and radiator when this happened. I am wondering, could this be a lower intake manifold leak or a cylinder head leak?

Photos attached. Thanks for any help.

Bruce

 

Based on location alone I'd say your thermostat gasket is leaking or the clamp on your rad hose is no good.

 

Did you put thread sealant on the bolt threads? Check to see if your radiator hose clamp is tight also.

 

Agree with both above posts...

My 78 does the same thing if the planets aren't aligned.

If you find that everything is tight, the possibility of the gasket being no good or the water outlet is shot...

 

:d:d:d

 

Thanks Allan R for your reply. Radiator hose clamp does seem tight. I will check on the thermostat gasket.

 

Thanks Oldscutlass for your reply. The radiator hose clamp does seem to be tight.
I can't say about the thread sealant on the bolts, I didn't rebuild the engine. I hope that the shop did do that though.

 

Thanks for your reply fdwheelman. I will check this out for sure.

 

If worst comes to worse, you would just have to drain about a gallon of coolant and reseal the thermostat housing and check it for flatness. Glad it was not your intake!

 

You may also want to pull the manifold bolts where its puddling 1 at a time, apply some thread sealant on them and reinstall.

 

I vote for the thermostat gasket. Common leak issue.

 

You and me both Pat. I'm not convinced that thread sealant on the bolts is all that important because the gasket goes completely around them to form a seal. It will help prevent rust on the bolt, but that's about all. The gasket is what stops the leaking.

 

Sure it couldn't be his 710 thingy, Allan R????

 

Do the bolt threads go all the way into the water jacket? If so, then you need sealer on the threads.

 

Hardy har har there girlfriend!! Not this time....but it's close to where the 710 thingy is!!!


One more thing to add to the gasket issue though:
Sometimes when a new gasket is installed, the old one doesn't get fully removed from the mating surfaces (on the intake or the housing) and that can cause enough of a gap to create a leak.

 

Wipe it all down with brake clean, stick a balled-up paper towel in the 'pocket', put some tape over it, and drive it for a day!
That'll tell you where it's coming from!!

 

Agreed either hose of housing. You can wrap a paper towel around the hose and top of thermostat housing. If you find it wet after the car sits and gets cold, more then likely it is the hose leaking. Drain some antifreeze out, remove the clamp and hose, clean up the housing apply a thin film of vaseline and reinstall hose and clamp. Place clamp on a slightly different spot on the hose. If towel is dry and antifreeze on manifold then it would probably be the gasket. R&R the gasket, use some GM Gasket Sealing Compound on the bolt threads and the gasket.

 

Yup

 

Hey there Allan R and cutlassgal, I jacked up the car, put it on stands and looked all over underneath the car for the 710 thingy. Could not find it. I thought it would have a big label on it that said "710 THINGY"
Went to see the mechanic and asked him. He said that since the new regulations went into effect, only the garage owner could order new 710 thingies. He asked me how many did I need, and I told him one blonde, one brunette and one red head :-)
They'll be in next week.

 

Thanks guys and gals for all of the replies. I will do the tests with the paper towels and see what happens and also make sure all of the bolts are tight and have sealant applied. You guys are great!

 

I did not know they came in colors now. Way to go!! Can I put in a supplemental order??

 

I have just finished doing a similar project...

It's easy, no need for a mechanic. Take your time. Clean all of the parts you take off, and it'll be simple.

Worst comes to worst, gotta throw a new gasket and some silicone at it.