Leak down question/read plugs

gijams · 08-20-2007, 06:43 PM

Greetings, First time rebuild on an 87, 3.2 In preparing for an upper (value guides) rebuild the car was brought up to running temperature and I did a leak down test on the engine. The numbers ranged from 4 to 9% leakage, good numbers for 94K. The car uses 1 quart per 400 miles + with whiteish smoke. What I don’t understand is why 5 of the 6 plugs are very clean and right now color (light tan) almost to lean but the engine doesn’t over heat. Cylinder 5’s plug looked oily, sooty and as if it was not firing till the engine was hot. Cylinder 5 leak down was 9%.

Questions: Do engines that need value guides still run clean plugs or is the engines smoke and oil consumption possibly coming from one cylinder? There are no engine leak on the floor.

One thought I had was to replace the distributor cap and rotor. the ignition wire to the cl. 5 and a new plug. Drive the car for 500 miles and look at the plug.

Or go a head and rebuild the heads and be done with it.

Gary

88-diamondblue · 08-20-2007, 08:23 PM

Gary,
Welcome to the board. You will need to rebuild sooner than latter. Did mine at 84,000 due to 2 broken head studs. The valve guides were shot and I was using a quart every 600 miles. 500 miles will probably not hurt the engine. The possibility of damaging the valves or seats is the only thing I can see happening. The guides let the valves move too much. Get Wayne's engine rebuild book as there is so much valuable information even if you don't do the rebuild yourself. Also plan on replacing the lower 12 head studs with steel studs as the dilavar exhaust studs are going to fail. Do use the search button to find hours of reading on rebuild questions.

Also we need to see pictures of your car before we can answer more questions

gijams · 08-22-2007, 05:11 PM

Thanks for the info, Michael. I have all the books. I just ordered the tools from pelican, for the top end job. The BB won't accept my images.

Gary

911pcars · 08-22-2007, 07:44 PM

Would need the results of your leak down and compression tests. You don't specify the results. Could be both valve guides and rings, but you won't know about the rings until you can confirm.

Sherwood

88-diamondblue · 08-22-2007, 09:53 PM

Gary,

Just kidding about the pictures of your car. Still want to see it though. Keep us posted as things get started. And will answer any questions aboutt the rebuild.

If your pictures are above 3mp then you need to reduce the file size to a 2mp size picture and the BBS will do the rest for you.

gijams · 08-23-2007, 04:22 PM

The car is set up for Xcross, I bought it year and half ago knowing the engine needed work. My race history is mountain bike, karts, motorcycle road racing and now Xcross.

Waiting for engine holding yoke

Gary

88-diamondblue · 08-23-2007, 11:05 PM

Great color. The fun is about to begin.