Granite 944

I installed a used engine in my car to use as a temporary (about a year? I've got the original in my garage, with the intent of rebuilding it).
I put some pretty cheap 30wt oil in it with a mahle filter. I've driven it now for about 450 miles. Oil pressure is real good in it. It smokes alot more than I like to see, even for a temporary engine, so I decided to change oil/filter again using 20-50wt Valvoline oil. I also decided to run a compression check while I was at it. I had car at temp, fuse out for the fuel pump, and throttle wide open. Spark plugs lightly oily, but far from fouled. This is what I saw, using two different compression gages.

#1: 195lbs

#2: 165 lbs

#3: 170 lbs

#4: 195 lbs

Car smokes pretty good, especially after a long deceleration and then on throttle again. Whatcha think? Broken oil ring? maybe replacing valve seals could cut down on the smoking a lot. I haven't done a leak down test (don't have the equipt.) But I'm also thinking about buying a new compression gage, and rechecking numbers again. Looking for thoughts on this since I'd really don't want to get to far into this engine,even though I think I already know what the ugly truth is.
Thanks!

emilysgranny

Do you know how many miles were on that eng. under 100k valve seals ,more then 100 could be rings but still would bet on seals ,over 140 -160 bet on rings.Just a rule of thumb,not gospel. Low compression could easily be either rings or valves. Long decel and then on it smoke is generally rings. A vacuum gage would tell you in a flash.

emilysgranny

Granite ; start the car up from a cold eng , does it smoke right away. If it does thats a good telltale of bad valve guides and seals. Remember to look for blue not black smoke. Blue is oil ,black is gas , white is water.

944Play

You might try another compression test with a teaspoon of oil in the cylinder being tested. If the compression comes up with the oil, it's probably rings.

Granite 944

The engine is from an 1985/2 with an automatic showing 97K miles (speedo and odometer not working). Yes it smokes from cold start up. not heavy, but definately there. It is definately oil smoke, not fuel related. Engine has a external oil leak coming from the bottom of the oil cooler housing just under the pressure valve which is getting worse quickly. I will have to remove and replace seals on this soon. Could be some of the smoking due to exhaust manifold splash.
Emilysgranny, I do have a vacumn gage. I'll have to get it out and review test process and see what that can reveal. Thanks!

Granite 944

Any help on using a vacumn gage on this car, and results interpretation would be greatly helpful also! Thanks!

Charlotte944

Manifold vacuum should be in the 18 to 20" Hg range with the engine at idle. Connect the gage to the nipple on the blue/black check valve at the brake booster.

The vacuum gage needle should be steady. A "pulsing" needle would indicate worn valve seals/guides, or sticking valves.

Vacuum at the Fuel Pressure Regulator should be 14" to 18" of HG.

Also, check the spark plugs for signs of oil fouling/burning.

Finally, oil burning will shorten the life of you O2 sensor. If you discover the engine is burning oil, I highly recommend replacing the O2 sensor once the oil problem is resolved.

Peckster

Those numbers are really high, did both guages read the same?

130 to 150 is on the normal range I think.

A badly carboned piston and head can push the numbers up.

Granite 944

Yeah thats what the numbers read on two different comp. gages I have.
Cliff, thanks for the vacumn info, I'll run this out and see what comes up, and thanks for the heads up on the O2 sensor! Probable tommorow morning I'll run more checks. Thanks!

emilysgranny

Peckster; the numbers you gave are for a turbo , I believe his is an N/A .

ACG

Granite's numbers are for a 944NA....

My 951 runs around 150 psi across the 4 cylinders...

My 944 NA runs around 190 psi...which is fairly standard....

Granite 944

Well I bought a new compression gage (didn't trust the others I had), ran two successive tests with engine hot:

#1 : 162lbs (1st time) 168lbs (2nd time)
#2 : 155 lbs 155 lbs
#3 : 158 lbs 160 lbs
#4 : 182 lbs 185lbs

Using a vacumn gage: steady 21-22 at idle. steady 26 at rpm 2000 to 3500. No pulsating or iradic needle at all, returns to 21-22 quickly after decel. Vacumn shows ok to me.

Labor day, can't get my hands on a leak down gage. But I put 80lbs of air into each cyl. while at TDC, and discovered very noticable air leakage at the oil filler and the boot just before the AFM. I used a wire to find TDC, and after hearing all the air come out, rotated engine around 1 revolution just to be sure I was at TDC and compression stroke.
Well, it kinda looks to me this engine is basicly in need of the whole rebuild also. I think I'll just fix the oil leak coming out of the oil cooler, and just concentrate on getting the original engine rebuilt ASAP. I guess I didn't get such a good deal on this engine after all. I can't imagine that the head gasket could cause all this leakage, or could it? Thanks for any input!

Kevin Baker

Air leaking down at the oil filler would be bad rings, but you knew that from the compression tests. And the air sound at the "J" boot would be from the crankcase ventilation dome, which connects to the elbow of the j-boot. So it sounds like the head should be OK, just needs rings.

Kevin Baker

By the way. What's up with that goat? You are in Washington, and that sort of thing only goes on in like Arkansas and Oklahoma right!!??

Granite 944

My wife loves goats! Has this picture framed, and in kitchen area. It kinda grows on ya huh! Besides, at the time, Skip's ostrich avatar was sort of a inspiration for this.
Yea, I forgot about the connector at the j-boot. Rings looks like the answer. But I think it'll have to wait for a while.
Thanks!