[Fot] LEAK DOWN TESTING CRANKCASE PRESSURES

[n197tr4 at cs.com]

 with our cam we were able to hold the crank in place and get readings.

made mistake in not checking compression before removing head, but it is an
extremely low time head.

will be interested in peoples thoughts on my leak down outcomes with respect
to crankcase pressures at speed.

thanks Scott,

Joe A








-----Original Message-----
From: Scott Janzen <sjanzen at me.com>
To: Joe Alexander <n197tr4 at cs.com>; 'Friends of Triumph' Triumph
<fot at autox.team.net>
Sent: Thu, Jun 23, 2011 11:09 am
Subject: Re: [Fot] LEAK DOWN TESTING   CRANKCASE PRESSURES


when I did this recently, i discovered I had to remove the rocker assembly to
get good readings, as the air pressure pushed the pistons to BDC and at that
point, one of the valves was always either starting to open or still closing
with the cam I have. Did not seem to be a safe way to hold the crank at TDC
where a closed valve reading would have been possible with the valve train
installed.
Assume you figured this out, but just to check the obvious . . .


I had had the engine overheat and a head gasket fail when I lost an alternator
pulley and was not watching my gauges (this car never overheated before . . .
).  I had the head milled slightly to get rid of warp, but the machinist and I
thought the valves and seats looked pretty good and just lapped them in.
Turns out this was not enough and leak-down results were still crappy because
the heat had distorted the valves and seats.  Took the head apart again, recut
the valve seats and valve faces, put it back together, incredible results with
a worst cylinder 4% leak-down, and that's with no ring or cylinder work.


Good luck!


Scott
GT6


On Jun 23, 2011, at 11:36 AM, n197tr4 at cs.com wrote:


 FOT








 This seems like it may be a good topic.

I was getting an undue amount of crankcase pressure at Topeka.(Just now
trying
to find the time to sort out)

At idle there are absolutely no engine oil leaks.  At 60-100mph the oil is
being pushed out in huge amounts. at every possible location.

This occurs in spite of otherwise very effective vacuum system we have used
with great success on the TR4 #197

Have never done a leak down test in all of these years or had one done. No
experience at all.

Results:  100/85   100/80   100/60   100/60

Pretty dismal readings if I did it correctly.

Head is off and new rings to be installed.

The benefit of FOT experience and knowledge would be greatly appreciated.

Thanks!

JOE A.
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