1984 190D compression test
 

:( Compression test today, #1-350, #2-300, #3-20, #4-325. Broken rings on #3? What else could it be?

Rings or valves. Pull the injector and put some mmo in it. Let it soak for a few days, crank it over to displace the extra oil and recheck the compression. If it's a stuck ring the marvel mystery oil will help free it. If that doesn't help the a leak down test is needed.

With compression that low I would think a stuck valve.

How does a valve get stuck?

Has it been run on WVO ?
Valves can get build up on the shaft that stops them going all the way up.

I think the po just ran diesel fuel. Im going to take head off and see what I have.

How about a head gasket issue?

Hi
Might be worthwhile to remove the valve cover and observe the #3 valve action & adjustment - before pulling the head.

A recent thread had 0 compression in cyl. #1 which was just too tight valve.- wouldn't close. Maybe a rounded cam lobe that wont open a valve?
Joseph

Headgasket will cause bad compression like that? Also what do I need to buy to get those head bolts out? What size are they?

That's so low it probabaly is a valve hung open or a hole in the piston. I agree exploring the valve train before removing the head. Its a lot of work to remove the head!

Given the other cylinders have respectable compression, I would first have a look at the valve/cam operation.

It is surprising that it doesnt start on 3 cylinders. I would try & start it once I checked under the cam cover. Just make sure you have a little gap on both valves for #3 & they come up as far as the other ones.

If it has a bad inlet valve you should be able to see & hear it blowing back through the inlet manifold when you have the air cleaner off.

If its rings/piston, you should see the problem as blowby.

If its a blown head gasket it should bubble in the radiator.

How does the oil & water look?

If its a piston/rings, it may need the motor to be removed.

Here is the test.....

take the injector off and pour a teaspoon or so of regular oil (or MMO or whatever) into the combustion chamber. Then do a compression test, if the numbers improve then you have bad rings.

if the numbers do not improve, you have a bad valve.

bad valve= a burnt valve that remains open during compression. this is caused by lack of maintenance specifically ignoring valve adjustments.

ignoring valve adjustments= as seasons change and the temperature changes, this somehow tightens the adjustment screws. it got to the point were the valve would stay open during combustion. the heat from the combustion weakened the stem of the valve. at this point the valve is toast.

report back when you do this.

Hydraulic lifters in the 601 = no adjustment.

Well started to remove the head today and got alot done, just cant get the fan off. The manual says to take out center bolt and remove fan, well I took the bolt off and the fan will not come off. What am I missing? Ill put some pictures up later.

you have the magnetic fan clutch.


once the bolt is out, begin wiggling or give it a light blow (using your judgment)

there may be some corrosion prohibiting the release

as a second measure, feel into the recess of the fan (around the center bolt) for any other bolts.

I am recalling a similar difficulty, but it was too long ago.