Urgent Help - Compression Test Number, are they OK?

[Kim1978]

I am looking into buying a bpu+ TT 6-speed with 43.000 miles on the clock. The car was throughly checked by a Toyota technician.

 

There were some issues

 

* small/slow leak from the transmission

* tyres are done

* low idle/occasionally stalls

* car is lowered and the exhaust is scraped/smashed

* engine/clutch vibration since a RPS stage 3 race clutch has been installed. I was told that was perfectly normal

* alignment needed

* small ding on front right fender

 

That really didn't worried me that much, what REALLY worried me was the compression test

 

#1 135

#2 115

#3 135

#4 125

#5 115

#6 130

 

First I think the numbers are very low, second, the difference between 1st and 2nd cylinder is about 17%. I was under the impression 5% is great, 10% is OK but shouldnt be higher than that.

 

I talked to the technician who said the numbers were low but he wasn't worried about them. He told me the numbers are on the borderline what is acceptable but he believed the main reason for being low are the aftermarket adjustable cam gears (set very aggressively) from Titan. He was also very certain those were the reason why the car idle very low and stalls now and then.

 

What should I do? The seller is letting it go for below market since he is aware of some of these defects but the compression numbers were a major surprise for him too. I would also like to point out, the seller seems very honest and he even paid for this whole car-check even though it was done for me.

[Tricky-Ricky]

Sorry but the compression discrepancy figures are not good, and the bit about the cam gears causing it is bull, possibly would cause then all to be low or high but would not account for the difference in cylinders, and unless it has high overlap/lift cams then the gears would not account for the bad idle alone.

You could always reset the cam gears and recheck the compression.

Clutch wise, if its a twin or triple plate then you will get some noise/rattle but it should not cause vibration once engaged, and if its single plate then no other than the usual gatrag clunk.

[AshBhp]

Them compression figures indicate rebuild time and cam gear remark, double bull.

[merckx]

The following figures are from the workshop manual.

 

 

Compression:oooo156 psi or more.

 

Minimum pressure:oooo128 psi.

 

Difference between each cylinder:oooo 14 psi or less.

[Kim1978]

Thank you for your replies.

 

I am leaning towards telling him to get a 2nd opinion and/or do a leakdown test as well.

 

FYI, I attached the inspection sheet I asked the technician to use.

MikeG0001.pdf

[Pete]

FYI, I attached the inspection sheet I asked the technician to use.

 

That could be quite handy for other members. Would you mind providing the original doc so we can host in the downloads area?

[Kim1978]

That could be quite handy for other members. Would you mind providing the original doc so we can host in the downloads area?

 

Of course. Why didn't I think of that before

 

I have it in excel format as well but not at this computer - I will upload that on Monday.

supra_check_list.pdf

[Kim1978]

attached is the checklist in excel format

 

you can just edit the "known problems" and "aftermarket part list" as you want it. This list was just for a '97 I was looking at but didn't buy because of those compression numbers

supra check list.xls