[Mozencrath]

Ok so I have a 95 1.9l. It suddenly died on the highway. We are getting good spark and fuel but no compeesssion. 0 in all cylinders except cylinder 1 has 30 psi. We took off the riming cover and the alignment is perfect!! What could cause this vehicle to have perfect timing alignment but no compression? Thank you

 

[agrowagon]

dropped valve seat maybe? not sure how you would check. or maybe rings how did the plugs look?

 

[juggalo]

i suspect the timing belt snapped

 

[pextor]

i suspect the timing belt snapped

jumped timing probably

 

[Mozencrath]

Wow im actually a little scared of the responses i got. I stated in my OP that I had 0psi in 2 cylinders, and 30 psi in the other two. I also stated that the timing belt alignment was spot on and here are the suggestions I got:

"Timing belt skipped" ??? I stated I checked the alignment.

"Valve seat drop" ??? Would not affect all cylinders.

"Timing belt broke"" ????

 

[juggalo]

how did u check the compression?

try pouring a tble spoon of oil thru the spark plug cylinders and check the compression again. if they rise then the piston rings need replacing or the cylinder bore is damaged. if not, ur head gasket is blown or the valve seats r not sitting properly. check the dipstick for any water driplettes or if the oil looks milky.

 

[denisond3]

If you took off the timing cover you could see the marks on the cam sprocket, but how did you know the bottom sprocket (the one on the crankshaft was lined up. Its not possible to see it unless the large pulley is removed from the end of the crankshaft. There is a "timing mark" on the pulley, that lines up with a mark on the timing belt cover, but that is not going to give you the proper line-up of crankshaft and camshaft. Its for checking the timing of the spark - which is always going to happen a few degrees before top dead center.

It has also happened that the crankshaft sprocket got a damaged woodruff key somehow, and has rotated relative to the crankshaft. It has also happened that the same thing has happened on the end of the camshaft; someone could have assembled that without the 'key' too. Either of these could result in an engine being so far off-time that the compression readings would be miserable low.

Are all four spark plugs in decent shape, none of them showing signs of mechanical battering? Im thinking of a valve seat that broke up of course.

 

[pextor]

"Valve seat drop" ??? Would not affect all cylinders.

you bet it can affect all cylinders. you didn't mention any weird noises in your original post here, but in this post:

http://www.feoa.net/modules.php?name=Fo ... ic&t=66733

you mention prior noises, which are certainly an indication of valve seat issues. like madmatt2024 said, the valve seat can be loose, fall down onto the valve, then get popped back in and be fine for a short time. if you hear that noise, that is your warning of imminent failure. once the valve seat breaks, the pieces can get sucked back into the intake, into the other cylinders. I personally have seen this, on at least two different cars. one the guy drove in to my friends shop, on 3 cylinders. when we took the head off, pieces of valve seat had come across from cyl #4 to cyl #3 and #2.

based on the lack of info from you "zomg my car just shut off! what's wrong with it??" we have to go with the obvious solutions first. Thats why we suggested timing belt, they will suddenly fail causing issues like what you described.

 

[Mozencrath]

The head is off and it appears the valve seats are all intact. The spark plugs are not damaged however the head gasket is severely blown due to coolant that looks more like sludge than actual coolant. None of the cylinder walls appear damaged.

"Valve seat drop" ??? Would not affect all cylinders.

you bet it can affect all cylinders. you didn't mention any weird noises in your original post here, but in this post:

http://www.feoa.net/modules.php?name=Fo ... ic&t=66733

you mention prior noises, which are certainly an indication of valve seat issues. like madmatt2024 said, the valve seat can be loose, fall down onto the valve, then get popped back in and be fine for a short time. if you hear that noise, that is your warning of imminent failure. once the valve seat breaks, the pieces can get sucked back into the intake, into the other cylinders. I personally have seen this, on at least two different cars. one the guy drove in to my friends shop, on 3 cylinders. when we took the head off, pieces of valve seat had come across from cyl #4 to cyl #3 and #2.

based on the lack of info from you "zomg my car just shut off! what's wrong with it??" we have to go with the obvious solutions first. Thats why we suggested timing belt, they will suddenly fail causing issues like what you described.

 

[denisond3]

For sure you need to either get that head milled - or a replacement rebuilt head that has been milled. I rebuilt one 1.9L engine where I took the block in for cleaning - and the machin1st showed me where there was enough corrosion on the top of the block, that it needed to be milled also. He took .006" off the top of the block, to get down to where there was no rusted region - to cause another head gasket to blow out. His impression and mine, was that after the first headgasket had blown, the prior owner waited weeks or months before getting a new head gasket; so the block rusted too.
In that rebuild, I reused all of the pistons, but used new piston rings, and new bearings (since it was all apart on my bench anyway).
Anytime you have a headgasket go bad, the coolant is going to absorb a lot of oil, and look like a dirty Starbuck latte.