[SCJF350]

I put a set of the new SCJ Heads on my 460, F350 4X4. I did retorque the heads @ 600 miles. I have noticed a small anti-freeze leak, drivers side when the truck has set for a day or two, on the cold days, under 30. After it is warm or on a warmer day like today 40+ it dosent leak at all. Seems to seep at the #5 cylinder area only. Enough to se a spot under the truck. The block was decked prior to assembly by the best machinest in the area, so I don't suspect that. I used Felpro head gaskets with compresson thickness of .051 I live in Minot North Dakota, the temps can be from 20 in the mornings & to 65 by afternoon. So is this typical of aluminum heads to leak when cold, or should I be looking into different head gaskets?
SCJF350

 

[Beoweolf]

No, it's not something to expect from Aluminum heads. There are many guys that are running them without any problems.

What "could" explain it. Just WAG; is either the heads or the block are not square. A high mileage block or heads not surfaced could be off just enough to leak when the engine is cool, but expand when hot.

I wouldn't look at that as being my first choice, but if you didn't check them both before the swap it could be a possiblity. I would think that given the expansion differences between Iron and Aluminum, its more likely than it would have been with the old head (same metal and they went through the same problems, so they were matched). Bringing a new part into the mix might have been enough.

They do make softer, thicker head gaskets for cases like this. Back in the day, before people were so precise...cast iron rings were used to re-ring an engine, while it was still in the car, .001 overise bearing were used instead of having a crank turned...all those "backyard mechanic tricks" were used to save some money for the guy that asked you to just get it running...it don't have to be perfect.

If you are running something like Felpro blue, they may not have enough "give" to seal new heads to the unmachined short block.

Like I said...just a Wild A** guess, its an idea that you can feel free to dismiss, ignore, toss asids immediately or as soon as something better comes along.

<font size=-1>[ This Message was edited by: Beoweolf on 4/6/06 4:23am ]</font>

 

[Sonny]

If you get to having to take it apart,straight edge the deck of the block and head-You WILL know then regardless.Don't be tempted to stop leak it with a pour in mix!

 

[Motorhead]

Are you positive it's not coming from the front corner of the intake, and just running down the thin gap between the block and head?

 

[FEandGoingBroke]

Hey Beo and Head... He said the Block was Newly decked by the best machinist around.... Therefore that pretty much rules out a bad block surface righ toff the bat....
The new scj heads probably should have went to the machinist to be checked and touched up if necessary... There's always a chance they were slightly off, even being new.

FE

 

[SCJF350]

Thanks for the replies to the leaking head. The block was decked by the best enging builder in the area, & the heads were brand new, so I don't suspect any of that. The intake has leaked in the past, but other than pukeing oil out the rear above 3500 rpm the anti-freeze leak has stopped. I have new intake gaskets & a couple valve cover breathers coming to fix that problem. Before I retorqued the head @ 600 miles it seeped just at the small gasket tab sticking out at the front. Now it is farther back & below. I talked to the machinest today & he said that it could be the Felpro gasket might allow some slipage / seepage when it is cold, being Fords have one less head bolt than bb chevys. He recomended Cometic Head Gaskets if I do have to relace it. They are @ $100.00 EACH, but he said he has never had one of them fail even up to 16:1 comprtession with out an O Ring. So I will keep an eye on it. It only leaks out on the ground & when it's cold. Spring is almost here. I'll have to look closer to see if it might be from the intake. Not an easy task,...those of you with bifogals will understand. Thanks
SCJF350

<font size=-1>[ This Message was edited by: SCJF350 on 4/6/06 11:50am ]</font>

 

[FEandGoingBroke]

Not having played with a 460 and aluminum heads I can let your machinist's last comment slide for a few moments, but, his one less head bolt comment came out of his arse... I run an '83 F-250 460 4V 4 X 4, and... That's just a silly (or is that ass of nine???

) comment... The head gasket should let NOTHING out of the engine bro...

Anyhow... I hope she keeps on truckin' for ya bro, for 100K and more!

FE

_________________
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<font size=-1>[ This Message was edited by: FEandGoingBroke on 4/6/06 11:53am ]</font>