tech/mental help needed: i believe i just cant continue with this any longer

jgfiveoh · Jul 20, 2006

i have a coolant leak(more like a seep actually) coming from the back of my lower intake as far as i can tell. i have had the upper and lower off three different times fully cleaning and regasketing everything. the last time around i put a bead of rtv around each intake port and coolant crossover on both sides of the gaskets and i still have the same problem. when i had it apart i noticed that the rear of the passenger side lower intake gasket was saturated around the coolant passage on the back of the head. the coolant collects in the little dip on the back of the block and runs down and gets everything dirty as well as stinks up my nice engine compartment. what else can i do besides redoing the intakes again. i've tried block sealers to no luck. is this an intake problem or a head(alum) prob? i'm about to take the heads off and just start over again.

a couple things that i wondered that might affect the ability of things to seal. when i rebuilt the engine i was somewhat naive and torqued the head bolts to 80 ft lbs on the shorter water jacket bolts and 65 ft lbs on the longer upper bolts. <----backwards to what i understand now. could this be the reason for the leak?

also the machinist shaved .007" off the deck on each side of the block. could this have caused things to be off enough to cause this? if so what is the remedy?

basically, i'm wondering if i need to take the heads off and start over? i'm about done f-ing w/ the intake

with all that said, sorry for the long post, but i feel i just can't continue to work on the car until this is fixed!

ps. BEWARE OF MENTALLY UNSTABLE STANGERS IN THIS THREAD

LEE93COBRA · Jul 20, 2006

what kind of intake gaskets are you using? Are you torquing the intake bolts? If so, how much?

8950HO · Jul 20, 2006

Not sure on those head bolt torque specs.Sounds like a big gap between the two.

Anyhow back to the intake.Did you retorque the lower bolts after running the engine a bit?

I`ve had to retorque my lower intake 4 times so far to stop minor coolant seepage at the front using Fel-Pro 1250 gaskets.

Many others have also had to retorque their lowers numerous times before they finally sealed up.It`s a pita.

I for one will never use Fel-Pro 1250`s again.

jgfiveoh · Jul 21, 2006

used the motorsport gaskets that are recommended (not 1250s) with the gt40x heads. torqued to factory specs of 25-30 ft lbs using the ford technicians sequence. i also torqued in two steps 15 then 25-30 ft lbs. yes i went back and retorqued them once after intalling this last time. yes the head torque isn't quite right, but what else do you guys think?

8950HO · Jul 21, 2006

Check the lower intake bolts again and see if there loose.
That`s where I`d start.

I have the 89 Ford Mustang shop manual.It say`s 23-25Lb-Ft for the final torque spec with stock heads.

Dayzed50 · Jul 21, 2006

One trick I've learned that been a huge help is to coat your intake gasket water ports (or the surfaces common to the intake and head) with permatex #2 gasket maker (not rtv). It is a non-hardening sealant and it will hold an incredible amount of pressure before allowing leaks. Once I started using I've never had a drop from any coolant passage. Works well on the timing cover water ports and water pump gaskets. Also, when preparing the surfaces for sealant use brakleen as it leaves no residue, some other cleaners will leave a slight glaze allowing water to seep around sealants/gaskets.

8950HO · Jul 21, 2006

Another great gasket sealing product is Hylomar Universal Blue.

This stuff is awesome for intake and water pump type gaskets compared to silicone.
Goes on thin and easy,sticks like glue and has unlimited assembly time.It never hardens and disassembly is easy.

It was developed by Rolls Royce to seal jet engines and is great for automotive use.

I use it.

1987stangman · Jul 21, 2006

8950HO said:
Another great gasket sealing product is Hylomar Universal Blue.

This stuff is awesome for intake and water pump type gaskets compared to silicone.
Goes on thin and easy,sticks like glue and has unlimited assembly time.It never hardens and disassembly is easy.

It was developed by Rolls Royce to seal jet engines and is great for automotive use.

I use it.

Even better that has always worked for me is Gold Copper spray, and you can buy it at most any auto parts store. I usually spray the head side only (if you spray the intake side it will be a PITA to remove later) and lay the gaskets on the heads and run my fingers over them, let them sit about 10 min and then finish up the install.

Swede958 · Jul 21, 2006

Another vote for non-rtv on the intake gaskets... I'd recommend some kind of gasket shellac like Indian Head or something like that. Normall comes in little cans with a brush- brush on all surfaces, let it get tacky, apply gasket and torque down. Normally good to go immediately.

SamSnyder · Jul 22, 2006

You say you rebuilt the engine. Were the heads or deck milled? That changes the block/head/manifold relationship. If so, you may need the intake manifold milled to match.

jgfiveoh · Jul 22, 2006

yes the block was decked .007" on each bank

LEE93COBRA · Jul 22, 2006

Have you looked for a crack in the intake or the head?

jgfiveoh · Jul 22, 2006

yes i have checked for cracks on both and found nothing. gt40 heads and gt40 intake were both brand new when installed and i have had this (small) issue since day one

LEE93COBRA · Jul 23, 2006

Did you ever say whether you used a thin layer of sealant on the water passages of the intake gaskets

jgfiveoh · Jul 23, 2006

yes i used a thin layer of "the right stuff" RTV made by permatex. i used it around the intake ports and the coolant crossover ports.

8950HO · Jul 23, 2006

Check the lower bolt torque.

fidstang · Jul 23, 2006

jgfiveoh said:
yes the block was decked .007" on each bank

Did you have the intake decked to match the block. If not it will cause a port mis-match and maybe the small detail you are missing in your chase for the leak.

Kaoz78 · Jul 23, 2006

+1 for the decking being the culprit. (CNC Machinist here)
Seven thou' may not seem like alot but, that can multiply itself when angles ( head to intake relationship) are involved. I wouldn't just have someone shave .007 off both sides of the intake. Make the machinist earn their money. Make him do the math, or you do it.

jgfiveoh · Jul 23, 2006

i have talked to the machinist about it before and he didn't think it would cause a problem. i will look into it more though. would i need to have the intake to head port sides of the intake machined or the bottom of the intake machined so that it sets lower? last time i had it apart i checked everything real close and it seemed to fit pretty tight although i prob cant get a real good idea w/o taking the engine out. so what do i need to have the machinist do to it?

jgfiveoh · Jul 24, 2006

ttt please

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