Leak down test

Jar727 · 02-03-2009, 09:10 PM

I'm looking for advice and an education on this. Ok just had a leak down test down and results were not good for #3 & #5 cylinders both showed 85%. All others tested good with just 2%. Engine has only 66,000 miles and most likely had valves adjusted around 40,000 miles. Its 85 targa 3.2L and needs valve adjustment according to the shop. They said it could be carbon build up since plugs were in bad shape or they said it could have a top end rebuild for around $5,000 which i do not want to spend. Car runs great pretty strong and only white smoke on start up which i understand is normal. What are my options? Anybody want to put their two cents in?
Thanks
Joe

Flat6pac · 02-04-2009, 01:48 AM

You ll have a hard time recognizing a 15% leak down. Set the valves and enjoy the ride.
I have an 88 in the garage with a 90+% leak on #1, now that needs a fix, the heads will be in the shop next week, steel lower studs and reassemble in time for spring

Bruce

lucittm · lucittm's Garage

When valves need adjusting, it usually means they are too loose due to normal wear rather than too tight. This would not have an impact on your leakdown test, IMHO, unless a previous valve adjustment resulted in an improper clearance that keept the valves slightly open. Also, carbon on the valves can cause a leak. You can tap on the exhaust valves with a brass hammer and see if that changes the readings.

My results were similar to yours except it was cylinders 5 & 6. My problem was broken rings.
I would adjust the valves, of course, and also check the torque on all the head studs while you are in there. Leakdown is usually attributed to head gasket, valve seats, or piston rings.
How is the compression on #3 & #5?

Good Luck,
Mark

Jar727 · 02-04-2009, 08:35 AM

We did not do a compression test only leak down. I have the car scheduled for the tune this friday by a local shop. He quoted me a price around $650 for tune up. At this time, he said he would do the compression test to see whats going on. Hopefully its just carbon build up. I have not been using high oct fuel and was told that was a big mistake with these cars. I do not have the money to spend on a top end rebuild and may consider selling her. If valves and heads are ok then i'm in a better position to get top dollar for her.

Steve@Rennsport · 02-04-2009, 10:16 AM

If I might add,......

The real value of leakdown testing is the ability to pinpoint WHERE any noted cylinder leakage comes from. If a technician doesn't investigate and write down the source of the results on the guage, he isn't doing you any favors.

Air leaks heard from the airbox-air cleaner assembly shows leaking intake valves.

Air leaks heard from the exhaust pipe(s) shows leaking exhaust valves.

Air leaks heard from the oil tank filler tube shows leaky rings.

This is how the numbers on the leakdown guage are quantified: 0-5% is about perfect, 6-10%is great, 11-20% requires some investigation, 20%+ shows a problem.

Compression tests do NOT tell you WHERE the source of any compression loss is.

Jar727 · 02-05-2009, 06:14 AM

Steve
Thank you for your information. It really helps and I think i starting to understand all this now. Do you then suggest i have them redo the leak down test in lieu of doing a compression test after my tune up and valve adjustment?

Steve@Rennsport · 02-05-2009, 03:42 PM

With all respect to the kind folks at your shop, I would have them redo the leakdown tests and take careful note of the source of any leakage noted on the guage as above.