[Bobcatmo]

This is the CAR
I ran my compression test.....disturbing

#1 - 175 (dry)
#2 - 35 (dry) 35 (wet)
#3 - 90 (dry) 105 (wet)
#4 - 120 (dry)

Checked valve clearances:

INTAKE - .015 .011 .014 .010

1 2 3 4

EXHAUST - .017 .017 .018 .018

Diagnosis???....I know it can't be pretty

 

[144]

Confirm that you ran the test with the throttles wide open.

Try pulling all the spark plugs, then rotation the engine while you take a look at the part of the valves you can see with a strong focused light. Check for damaged valves and pistons.

Was the plug color different on #3 or #2?

 

[ghnl]

A leak down test will give you a ot more info - and allow you to pinpoint the source (or sources) of problems.

My eL-cheapo version is just a hose that screws into the spark plug hole and attaches to an air line. Position the cylinder being tested at TDC on compression and apply 60-80 psi via the hose. be careful - the engine can suddenly turn.

With the cylinder pressurized, listen at the exhaust pipe, intake, adjacent cylinders, oil fill, radiator and around the edges of the head. It is normal to hear some hissing past the rings (heard at the oil fill) but not at the other places. A real leak down tester has a pair of gauges to measure how well the cylinder will hold air. My version just allows you to look for problems.

BTW, was your compression test done with the throttle(s) propped wide open?

 

[Bobcatmo]

I am ashamed to say that the the throttles were NOT open......I wasn't even in the car....just reached in and turned the key.....I will check it again tomorrow...(should other plugs be in or not, the first test had other 3 plugs in)

 

[GTV4EVR]

Pull out the fuel pump fuse
Remove all spark plugs
put the tester on a cylinder
Foot to the floor on the gas pedal
turn the key
repeat for other cylinders

 

[Tifosi]

In theory, using the above methods, you should see max pressure at each cylinder in around 5-6 rotations of the engine. (2-4 seconds cranking)

Cylinders that are slow to build compared to the other cylinders may also represent a problem.

 

[144]

Also:

Run the starter long enough to get 6 or 7 compression strokes on each cylinder. Note how the pressure builds. It should have a really good boost in the first couple compression cycles, then build slower to max.

 

[sfisher71]

In addition to all the good advice, one observation: traditionally, if two adjacent cylinders are both low, that suggests there's a blown head gasket between them. Be sure to look up the bad-head-gasket thread (short version: Reinz made a small run of head gaskets that were not suitable, be sure you don't get one of those if that's what's wrong).

Your numbers should come up if you open the throttle all the way; a good reading for an Alfa 2L with proper compression should be in the 175 range.

 

[ghnl]

Throttle(s) should be propped open, all spark plugs out and the battery must be fully charged. If the battery is weak the cranking speed will get slower & slower (especially if you left the spark plugs in) which could explain the low reading in #4.

Are you sure the tester was tightened fully into cylinder #2 & #3?

 

[Bobcatmo]

RE-Compression test

Ok....redid the compression test....foot to the floor...all plugs out....tester tight (tested twice)

#1 - 120
#2 - 35
#3 - 175
#4 - 155
(I am suprised in the difference)

I believe the timing chain is not the original....there are scoring marks on the valve cover and no wear marks on the chain....can someone tell from the photos or tell me (idiot's guide pls) how I would be able to verify "cam timing" and could that be a source of this problem (many more to follow)....

 

[ghnl]

To verify cam timing position the #1 piston at TDC on compression (the cam lobes for #1 will be pointing away from each other - i.e. the intake pointing right and the exhaust pointing left.) There should be a pointer on the bottom of the water pump and marks on the crank pulley. 'P' for TDC and 'F' for ignition timing.

However, as the pointer is adjustable it could be mis-adjusted. I like to get it close then use a drinking straw as a poor-man's dial indicator to make sure the piston is at the top of its stroke. The straw is stiff enough to work yet soft enough that it won't hurt anything internally. When you think the piston is at TDC, put the straw into the spark plug hole and move the crankshaft back & forth while watching the straw to see if, indeed, the piston is at the top of its stroke. When you are certain it is, see if you can find the marks on the crankshaft pulley.

Back to cam timing - with the #1 piston at TDC on compression, the cam's timing marks should align with marks on the back of the front cam caps (away from the timing chain side).

Having said (written) all that, it is unlikely that improper cam timing would cause one cylinder to read so low. Something is drastically wrong with that cylinder. Either a valve is not sealing, the head gasket has failed, rings are broken or the piston has a hole in it!

I suggest the leak down test. See my previous reply for my eL-cheapo version. That'll tell you where the problem(s) is (are).

And before you tear it apart, you might want to try re-torqueing the head. Can't hurt (but unlikely to affect a lasting repair...).

 

[ghnl]

Here's a picture of what the timing marks on the cranshaft pulley look like. This is on a pulley I cleaned and then highlighted the marks with a bit of silver paint. Otherwise, they are much harder to find. You'll probably need a small wire brush to clean off any crud first.

 

[rogerspeed]

At the risk of being wrong, again, the chain is a hard steel, the valve cover soft aluminum, the wear marks indicate at one time the chain was not tight enough, hence the wear. You could spend time checking the timing, but #1 & #4 are symetrical in operation, so your problem isn't the cam timing. The clearences are off for stock cams but not the problem, as #2 & #4 are similar but different compression. I don't think stuck carbon on the valves&seats explains it either. The most expedious step is to take the head off to determine the internal problems such as, faulty head gasket, cracked head, bad valve (bent/burned/etc) bad valve spring or seat, bad liner/piston, etc.

 

[ghnl]

I agree that it is most likely the head will be coming off sooner or later. I like to have a diagnosis first though. Sometimes taking things apart too soon makes that difficult or impossible. For example, if the head gasket has failed, removing the head will probably ruin the gasket making it difficult to 'prove' that was the problem.

However, being the frugal guy that I am (OK, cheap...) I don't like to waste a lot of money to make the diagnosis. Thus my eL-cheapo leak down tester should pinpoint the problem(s).

One other thing to try before tearing it apart is to peek into the #2 spark plug hole while turning the engine over. You will be able to get a glimpse of the valves as they open & close. If they don't - big problem! (bent/broken valves). If they do, see what the edges look like. Any chunks missing means burned valves (and probably seats, too).

Finally, if the valves move and aren't missing any pieces, try using a screwdriver levered against the camshaft (not on the machined lobes but against the rough casting of the camshaft) to open & close them a few times. Do this when the lobes for #2 are facing away from the engine. Pry the valves open and let them 'slam' shut. If there is carbon built up on the seats, that may knock it loose. Then crank the engine over for 10-30 seconds (spark plugs out) to blow out the crabon and re-do the compression test. Remember to keep the battery fully charged and prop the throttle wide open.

 

[sfisher71]

In my (limited) experience in head-gasket problems, they are REALLY OBVIOUS once you get the head off. The last one I saw had a 2" piece of gasket completely burned away from the circumference of the #3 cylinder, right next to the exhaust valve. No question why THAT cylinder was low!

And as a fellow cheapskate, if it's NOT the head gasket, you'll still have to put in a new gasket when it goes back together, no matter whether the root cause was a valve or a holed piston or a broken ring. So even if the gasket hasn't failed, it has to be discarded for the sake of the rest of the engine.

So at this point... it really sounds like you need to pull the head to find out about the low cylinder(s). Anything you tell yourself to the contrary is just delaying the inevitable. Cam timing affects ALL cylinders (I looked, and there doesn't appear to be a giant hunk of metal on the #2 cam lobe causing those valves never to close ), so if just the one is super low, it is now time to pull the head and find out what's going on.

 

[John M]

Just a guess at this point, but I speculate you need either need the head rebuilt or you have a blown head gasket. That tight clearance might have resulted in a burnt valve or it just may indicate its been a long time since anyone adjusted her. 4 is too tight although some people run really tight clearances across the intake side.

Redo the test with a cap full of oil in each cyl. If it comes up significantly it indicates rings. If it doesn't come up...indicates gasket or valves. I am wondering about #1 since it is way low compared to 3 and 4. If either 1 or 2 come up significantly with oil....consider pulling the motor and refreshening it all.

I am guessing at minimum you are looking at some valve lapping, reshimming, and reinstalling. And if you want to do it right if it hasn't been done in 4-5 years....especially if the car is using oil, install new guides and stem seals for sure and valves if necessary.

Best Regards,
John M

 

[Bobcatmo]

I have figured that I need to redo the head.....have almost convinced myself to just pull the engine and go over the whole thing (have never done it before)......

To verify cam timing position the #1 piston at TDC on compression (the cam lobes for #1 will be pointing away from each other - i.e. the intake pointing right and the exhaust pointing left.) There should be a pointer on the bottom of the water pump and marks on the crank pulley. 'P' for TDC and 'F' for ignition timing.

I checked the timing for giggles (still have carb issues) and have seen these marks with the light....I figured I would have to do some cleaning to the pulley also...

However, being the frugal guy that I am (OK, cheap...) I don't like to waste a lot of money to make the diagnosis. Thus my eL-cheapo leak down tester should pinpoint the problem(s).

Being frugal myself, I was smart enough to get a compression tester with a quick release....to my fortune, it is the same release my air compressor uses....what PSI should I push through and what/where should I listen??

One other thing to try before tearing it apart is to peek into the #2 spark plug hole while turning the engine over. You will be able to get a glimpse of the valves as they open & close. If they don't - big problem! (bent/broken valves). If they do, see what the edges look like. Any chunks missing means burned valves (and probably seats, too).

I looked into the cylinder and it seems that #2 is the only one that looks clean, but I am not able to see much of the valves, I haven't tried looking while the engine is turning....

Redo the test with a cap full of oil in each cyl. If it comes up significantly it indicates rings. If it doesn't come up...indicates gasket or valves. I am wondering about #1 since it is way low compared to 3 and 4. If either 1 or 2 come up significantly with oil....consider pulling the motor and refreshening it all.

I figured I would have to do it wet so I put the oil in first this time....didn't bother with a dry run...



Who wants to come over for a head rebuilding party??????

 

[gprocket]

My $.02: Pull the engine. It is pretty straight forward and gives you the chance to go over everything in the clear light of day.

 

[John M]

Bob:

If piston is clean on 2 then probably a blown head gasket. Was she smoking white on decel?

Best Regards,
John M