[Supras] Thread size, exhaust studs and oil leaks

[-Rich]

I'll second Hacker J.

1.) the AL head should not be tapped and re-used.  The AL notoriously 
weak around the exhaust manifold.  Helicoil it and forget it.

2.) the valve cover gaskets and the rear main are the only to major leak 
points but the fan tends to throw oil/power steering fluid (ATF) and 
coolant all over the place if you're leaking.

-Rich


Hacker J wrote:

>The standard wisdom is that the exhaust manifold threads in the head need to be helicoiled. They
>tend to be a weak point and over time begin to strip out.  The thread is M10x1.25.
>
>You can use the HeliCoil 5543-10 Repair Metric Kit for M10x1.25. It can be done without removing
>the head, although you need a right-angle adapter for your drill since space it tight.
>
>Also, be sure to use all the stock manifold bracing to support the weight of the turbo and ease
>the  load on the studs.
>
>There is not much that leaks oil at the back besides the valve covers.  However, the engine is
>tilted, and oil tends to run from front to back. It is possible that the head gasket is leaking,
>although pressurized oil is only supplied at the front. At the rear exhaust corner there is an oil
>drain from head to the sump, and the stock headgasket is weak in this area. Also, the oil
>feed/drain for the turbo can leak. I would suspect it is more likely you have a leak up front (CPS
>o-ring, cam seals, valve cover) and it is running backwards.
>
>Jon 
>90T
>
>
>  
>
>>>From: "Mike Long" <milisake at gmail.com>
>>>      
>>>
>>Subject: [Supras] Thread size, exhaust studs and oil leaks
>>Date: Mon, 8 May 2006 23:21:59 -0400
>>To: supras at supras.com
>>
>>Finally took off the turbo today and found the exhaust manifold to be
>>quite loose.  So loose I was able to hand-turn one of the studs out
>>and the others didn't take too much persuasion to get out either. 
>>Whoever put this car back together didn't know what they were doing. 
>>The thing was so loose, the gasket was black to the edges from exhaust
>>gas escaping around it!
>>
>>I'm going to pick up a new set of studs and nuts and would like to use
>>a thread-follower/tap to clean out the threads before I mount
>>everything back up.  Anyone know the thread-pitch and size I should
>>use to do this?  I'm going to pick up another manifold while I'm at it
>>too.  It appears to have been repaired once and has a sizeable crack
>>third leg from the front.
>>
>>I think I also tracked down my oil leak.  Besides the valve cover
>>gaskets, what else at the back of the engine would leak oil?  Fluids
>>aren't mixing and it doesn't seem to be coming from the head/block
>>junction.  It's also a slow leak, but significant enough to have
>>leaked down one of the braces and on to the exhaust.  Don't feel like
>>driving around in a fire hazard.
>>
>>Cheers,
>>Mike
>>
>>    
>>
>
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