Intake manifold coolant leak

[johnbeck]

My engine rebuilder installed the aluminum Edelbrock Performer manifold on to the cast iron 302 and aluminum AFR heads. The rebuilder and I were attempting to do the engine break in and ran into challenges. The distributor appears to be off a spline - not continuing to run, the fuel pump's discharge fitting wouldn't seal, and coolant was dripping out of the intake manifold to the front of the engine block just behind the distributor. A small amount of coolant was running down the engine front. A friend suggesting testing the torque on the intake manifold bolts. Am I best off pulling the manifold and sealing it myself? How common is it for a newly installed intake manifold to leak? How common is it for coolant to get into the intakes or cylinders? I haven't written a suicide note yet, just hoping to work my way through what I hope are the final challenges to getting back on the road. Thanks for your suggestions, John B

 

[anoblefox]

The coolant leak COULD be at the thermostat housing, hopefully you are not using a chrome stat housing, typically import manufactured and the cause of lots of leaks on SB Fords over the years. It would be prudent to re-torque the intake to see if that could be the cause.

 

[blubuckaroo]

Do you know what type of intake gasket was used? The ones supplied by and recommended by Edelbrock have a bad record for water and intake runner leaks. If it has no steel support layer, it has trouble staying in place. I use the newer FelPro 1250s3.

A tooth off on the distributor isn't a problem unless you can't rotate it enough to make a proper adjustment.

 

[B RON CO]

Hi, X2 on checking the thermostat housing and all the hoses and clamps. If the thermostat slipped down, which is common on the Ford thermostat, the housing cannot seal and you may crack the housing if you just tighten it. If you dry everything and think the leak is from the thermostat housing I would remove it make sure the thermostat is seated in the groove. I put the thermostat in the groove and glue the gasket to the housing to hold the thermostat. This Ford design can be a pain in the a$$.
If the coolant passage is leaking water I think more water will leak into the valley and drain to the oil pan. Check the oil level. More likely then going into the cylinders
Do not run any engine with a fuel leak. Hopefully that is the easiest to deal with.
Is engine builder should help get it running?

 

[Rustytruck]

before you run again go to the auto parts and rent/borrow an engine coolant tester, pump the cooling system up and find the leak. fix the leak so you can move forward.

 

[johnbeck]

Thanks All! As Rustytruck advised, Get a coolant tester, pump the pressure up, and find the leak so I can move forward. Thanks Blubuckaroo for the information on the Edelbrock gaskets history. I'll try to hunt down the "newer Felpro 1250s3 gaskets" and check the engine oil level for coolant. Once again, thank you all for your support. John B

 

[nvrstuk]

I would be extremely concerned if your rebuilder didn't have an answer to all of your questions and a FIX that he would discuss with you before you even had the opportunity to ask what the problems were.

 

[72Sport]

Thanks All! As Rustytruck advised, Get a coolant tester, pump the pressure up, and find the leak so I can move forward. Thanks Blubuckaroo for the information on the Edelbrock gaskets history. I'll try to hunt down the "newer Felpro 1250s3 gaskets" and check the engine oil level for coolant. Once again, thank you all for your support. John B

The after market thermostat housings vary quite a bit In the area the thermostat sits. I have seen housings that the depth of the pocket where the thermostat sits is too shallow. The gasket should seat around the perimeter of the thermostat and the bolt holes. You need the housing to seat on the perimeter of the thermostat housing and the bolt holes. If the thermostat sits too high or the pocket is too shallow the ears of the housing get bent when you tighten up the bolts and you bend the housing so it doesn't seal (forever). Eventually the gasket will compress and allow coolant to seep around the perimeter or through the bolt holes. The thermostat will hold open the seal between the housing and the manifold. You don't need to have a tight seal between the thermostat and the manifold. If you look at a thermostat you can see the dimples in the id of the thermostat which are air passages so the air can escape and allow coolant to fill the area around the thermostat. If you shop around you can find aftermarket thermostat housings that allow the thermostat to sit far enough in the housing so the thermostat doesn't weaken the seal around the mounting bolts or cause the housing to bend when tightening the 2 bolts that hold the thermostat in place.

I made a fixture so I can hold the housing in a mill vice and machine so the cavity is deep enough. Mine has not leaked since I modified it over 10 years ago.

 

[johnbeck]

I'm going to use a Stanton pressure gauge and test my engine to determine if I have a coolant leak from the front of the intake manifold. Any precautions I need to take? I have an old instruction manual for the pump. Unfortunately it doesn't list a maximum pressure - perhaps the pump is limited it's self by design. Thanks, John B

 

[73azbronco]

Well, your rad cap is probably 15-17 psi so not much more than that.

 

[johnbeck]

I would like to do a coolant test before attempting an engine break in again. Can I do a coolant system test with a cold, non running engine? Will gasket leaks be visible? I would think very small gasket leaks may not be visible until the heated metal components expand. I need to verify the intake manifold leak before I tear off the the carb., the distributor... I had a fuel leak at the time of the attempted break in and had to put off investigating the running coolant from the intake manifold area. At worst I'll have to remove the intake, install new gaskets, and hope for the best. Any thoughts? The cold, non running test likely to show a leak? Pressurize for how long? Thanks, John B

 

[SHX669]

Well if you have to take off the intake then when reinstall use a thin coating of silicone around the water passages- been a long time standard procedure - also a thin coat on the thermostat housing gasket .

 

[B RON CO]

Hi, yes can do the cooling system pressure test cold. I think your water leak is big enough and you will see it right away.
If the engine was broken in you could run it with the pressure tester attached, but I would not do that on your engine. I would focus on the break in.
The old tester is a Stant. I think you will find the leak right away with just a few pumps, without building up too much pressure. Just make sure the water level is so you can see it in the radiator. You can leave the system under pressure as long as you like. Does it drip just sitting there?
Good luck

 

[72Sport]

I had similar problems Many years ago with a leak from the bottom two bolts that hold the backing plate on the water pump. The two bolts on mine looked like they were modified. Most bolts or screws have a relief around the hex head of the two bolts. Edelbrock took stock screws and machined the head down so the heads were shorter than a stock bolt so they would clear the front the engine. They cut the hex from the side closest to the backing plate. The sharp corners were left on the hex. The sharp corners on the hex or wrench flats would dig into the backing plate causing the backing plate to bend around the bolt head and leak. A friend with a Mustang replaced the two bolts with button head screws and solved his leak problem. I decided that the backing plate was too thin so I make a thicker one. I also replaced the Edelbrock bolts with grade 8 bolts which I had the head modfied to the same height as the stock bolts by cutting the down from the top of the hex and leaving the underside of the had as it was received from the bolt supplier. The new backing plate was the same thickness as the gasket and backing plate. No gasket was used. I used silicone only to seal the backing plate. It has worked fine for the last 15 years or more.

After having the above problems I stopped by Edelbrock plant in LA. They said they never had a problem. Maybe that changed later on.

 

[73azbronco]

Well if you have to take off the intake then when reinstall use a thin coating of silicone around the water passages- been a long time standard procedure - also a thin coat on the thermostat housing gasket .

Mmmm not in my experience. Except for silicone at front and rear of intake, only thing sort of needed and not really needed is something like Indian Head shelac or copper coat spray, on intake gaskets/ both sides. My experience the silicone around the water ports and air ports shifts and can actually cause leaks. Dry install with the shelac is best, and closer to factory. The thermostat, yes, thin layer both sides of thermostat itself and then only on housing while you install.

 

[nvrstuk]

johnbeck- I hope you get this together and it works good for you.


I still can't understand a "rebuilder" that didn't fix this before you ever got to take it out of his shop.?????