First of I want to apologize for the length of this, but I need to figure out a few dilemmas.
A while ago I did some additional mods to my car at a local shop (downpipe, air intake, FMIC, BOV, plugs, egr block, fluid change and suspension). They noticed that my motor was a little noisy. So they decided to check the valve clearances and confirmed that they were loose. But they never adjusted them (not sure why). They also did a compression test on the car and reported to me that #3 and #6 cylinders were quite low.
These are the numbers they reported to me:

cyl 1 - 155
cyl 2 - 155
cyl 3 - 130*
cyl 4 - 150
cyl 5 - 160
cyl 6 - 125*

They also did a leakdown test and reported these numbers:

cyl 1 - 10%
cyl 2 - 6%
cyl 3 - 30%*
cyl 4 - 10%
cyl 5 - 12%
cyl 6 - 60%*

I was pretty surprised to see those numbers (cyl 3 and 6) because when I bought my car the previous owner had rebuilt the motor and when I bought it, it had approx 5000 kms on the engine. So I was bummed out because now I'm thinking I have to spend money on a new shortblock. Also, at idle, my motor sounds kinda like a diesel engine (that's the best I can describe it). Now when I bought the car, I had never heard the sound of a supra engine while it idles, so I didn't think anything of it and when I heard another supra at idle it purred and sounded much quieter than my car. My car has a Ross forged pistons in it and I'm not sure if that has anything to do with the diesel sound (ie. piston clearance, or piston expansion properties). Attached is a link to the piston spec sheet I was given when I bought the car.

http://members.rogers.com/gotjam/Piston%20Spec%20Sheet.jpg

Or is the rattling/ticking because the vales are loose. Anyhow, I decided to my own compression test before going out and spending money on a new shortblock and I also did a leakdown test and checked my valve clearances.
These are the numbers I got:

Warm Compression Test
cyl 1 - 170
cyl 2 - 170
cyl 3 - 175
cyl 4 - 170
cyl 5 - 170
cyl 6 - 175

Cold Compression test
cyl 1 - 170
cyl 2 - 170
cyl 3 - 170
cyl 4 - 170
cyl 5 - 170
cyl 6 - 165

Leakdown test (cold engine)
cyl 1 - 10%
cyl 2 - 17%
cyl 3 - 11%
cyl 4 - 15%
cyl 5 - 19%
cyl 6 - 14%

Valve Clearance (cold engine)
cyl 1 - int .010 / .011 exh .016 / .014
cyl 2 - int .009 / .009 exh .017 / .017
cyl 3 - int .011 /.008 exh .017 / .014
cyl 4 - int .008 / .010 exh .013 / .017
cyl 5 - int .009 / .008 exh .016 / .015
cyl 6 - int .010 / .008 exh .022 / .017

I know the valves are loose as specs for intake is .006-.010 and exhaust is .010-.014 so can this be the culprit of my noisy motor or is it the bottom end? I think it's the top end as the leakdown #'s would be worse if it is in fact my bottom end (correct?).


Now my question is why such discrepancy between my compression and leakdown test results and the shop? I was not present when the shop did the compression test or leakdown test and not sure if they did it cold or warmed the engine. I figure since they are a shop they know the procedure. They have worked on supras and have a few other supra customers. Are they just trying to get me to spend more money? I have all these thoughts in my head.

Can anyone help me with the above?

Danny

What procedure did you use for testing compression?. The diesel sound is probably coming from too much ring clearance (is it louder on cold start than warm?) or in a worst case bottom end noise from wrist pin or bearings. It is not totally uncommon for some running forged pistons to have some cold start noise and then quiet down some with heat expansion. What oil do you run?

Does the car smoke at any time during operation? First start, idle, or under boost? If so, what color is the smoke?

Compression test should be done with a warm motor, fully charged battery, throttle to the floor. Leak down is the more tell-tale measurement and while the numbers are not great, they are not horrible as well.

Mark Tozer
94 Supra 915HP
RPS T72
AEM Stand Alone
Black 6 Speed

Thanks for the reply Mark,

We did the compression test exactly how you outlined. I went out prior and did a nice highway run to ensure no carbon buildup. The 'diesel' sound is present more so when the engine is warm. I currently have castrol 10w30 oil in the car (just did the oil change a week or so ago). When we checked the valves the inside of the valve covers were perfect. golden oil film and no shrapnel. I was contemplating using 15w50 oil, but not sure if that's too thick. Our weather here isn't as blazing hot as in Arizona.

My friend advised me that at startup it does smoke a bit blue (indication of valve seals) and it does let out a bit when I let go of the acceloerator after I go for a hard run. The color of the smoke is blue but more black.

Also my friend wanted me to mention to you that While the car was idling he cancelled the spark on each cylinder to see if the rattling/ticking would be cancelled out but it wasn't. Not sure if that test would be an indication of anything.

Did you have a chance to check out the piston spec sheet? Are they the proper specs?

What would you recommend I do? Screw it and buy a new shortblock? I do plan on going t66 and I want to make sure I'm not wasting money on items that I don't need. If i have to get a new shortblock then the single is gonna have to wait a year or so

[This message was edited by Danny T on September 09, 2002 at 08:03 PM.]

"The 'diesel' sound is present more so when the engine is warm"


---I made an error on that quote, the 'diesel' sound is more evident shortly after startup hile I'm waiting for the car to warm up.