Hello everyone, as you can see I am new here. Two weeks ago my timing belt stripped out while I was going around 30 mph. I was on the street that my house is on and I was able to coast into the driveway. I did try to start the car after it died and that is when I realized that the engine was turning over extremely fast. I knew that I had no compression at that point. Well here is where it gets confusing for me, first I understand that this is an interference enigne. I commence to replace the timing belt, tensioner, and idler. Once I had these items replaced I tried to start the car just to be sure everything was ago before re-installing all of the other belts. Well to my disbelief I still had what appeared to be no compression. Well last night I got out my compression gauge and again to my disbelief I had no compression on all 4 cylinders. I understand that I may have warpped a valve of damaged a piston on this interference engine, but all 4 cylinders????? If the No.1 is at TDC I cannot get compressed air to pass through the cylinder but when turning over the engine with the starter there is no compression and this is the same thing cycling through all the cylinders on the compression stroke. If I open each cylinder one by one I can get air to pass through to the intake and also and then with the intake valves closed I can get air to pass through to the exhaust. I am reallly confused, my thought is that I probably damaged a valve but my gut is telling me that I may have something else screwed up. Any help or direction would be greatly appreciated.

Thanks, Gary

Hello Deercamp

Im sorry that I cant help you, hopefully someone on this forum will. But I do have a question, how many miles or km did you have when the belt went?

you have bent some or all of the valves, you will need to remove the cylinder head to investigate further

Thanks for the info, I will remove the head tonight and see if that reveals anything.

Montega is probably right on this.
However if the valves are warped there should be at least some major leakdown of the compressed air when introduced through the sparkplug hole at TDC,due to non sealing of the warped valve.
Though valve damage is likely ,it could be that the cams are out of time with the crankshaft,(open on compression and/or power,closed in intake and/or exhaust.)It only takes a few teeth to mess everything up .
I had a belt strip twice on a Ford/Mazda interference 2.0 and never any piston or valve damage.
Good luck :57:

This post has been edited by Tango2Go: Sep 10 2008, 02:48 PM

is it under warranty???

I almost bought an sx4 for the simple fact that they have timing CHAINS. I lost my mazda 626 (loved that car) to a timing belt. I thought I stalled it, started it back up and drove it a block.

...then parted out the car and sold it to a junkyard.

I'm scared for my accent. You know my timing belt will be changed at 29,000 miles.

I definitely want to know how many miles, I'm at 42k on my '06... Timing belts give me the willies, but I knew what I was getting into going into this. Nothing like a good ol' chain, man... :(

Hope you can get it fixed! Let us know what you find when you tear into it. Is it not under warranty?

This post has been edited by hoosieraccent: Sep 10 2008, 08:04 PM

pull off the valve cover, should be easy to see if the valves are bent. If they're bent, they wont come back up all the way. Also, if you're still not sure, when you have the valve cover off, put it to the point where one cylinder looks as if all the valves are closed and then shoot some air into that cylinder, if it wont hold the pressure.. well.. time for a new head or valve job

how can you see if the valves are bent through the valve guides??
He would need to see the bottom of the head to see how the valves are seating.
A compression test would be the better way to test this.

If the engine is turning over really fast (i.e. no compression at all)
I would think that the cam timing is off. Keeping the engine at TDC and aligning the marks on cam gears is the biggest PITA.
If you get it wrong, even by a tooth, you wont know until you fire it up.

A leak down test in this instance would be irrelevant since you want to see how the valves are sealing, not the piston rings.

I didnt catch this part. Can you please elaborate on how you tested compression on your engine? Like the step by step process you used.

What he said about looking under the valve cover.... if the valves are bent they wont be able to seat in the head.... so you can look at each vavlespring and se if it is coming all the way up when the lobe is on the closed part of its rotation. i hope this makes sense. if the valavs are even slightly bent you wont have any compression. makes sure you have it in time if its not in time you wont have compression each. the motor will make a chug noise noise if its out of time followed by a ... i dunno almost like a drop noise(like you would here from a leaky facet) at any rate you should hear that it dosnt sound right when you turn the car over. hope you get it fixed!!




on a side note timing belts statistically last longer then chases and are easiser to work on and less noisiey. also timing chains need a cover to hold oil in to keep the chain lubricated ...and they always leak lol every manufacture seems to have this problem. also when chains break looooooooook out!!! they break and chip up every think in there path haha... anyways just my two cents. i am pro belt!!!!

They won't come back up. That's how you can tell. Not every single valve will be bent, so it's quite easy to compare them. The ones that are not bent will seat properly, the ones that are, will stay in the hole and have a lot of play between them and the rocker.

How would a leak down test be irrelevant? If the valves are stuck open it won't hold any air, if they are closed it will hold air.

I know this is not exactly an answer or anything, but I thought I would ask here rather then start a new post.

Is the timing belt under warranty? And if so, how long it is under warranty? Would it be included in the 100,000 powertrain?

It is relatively simple to check the sealing of the valves also.
Remove the plugs.Starting with the number 1 cylinder at TDC,introduce air and see if it is sealed.Rotate engine 180 degrees and test the number 4 cylinder.Repeat with the number 3 cylinder ,then the number 2.
If some are sealed and others not you have warped some valves or hole in piston.If none seal either the cams are out of time OR you have warped all valves.
You will also be able to see the valve stem heigth when doing this.
Good Luck :57:

leak "DOWN" test. You do a compression test, then put a few drops of oil in the cylinder then repeat compression test and see if the compression number went up.
If not, then your piston rings are sealing fine. I have not heard of bent valves scoring cylinder walls before. That would be a catasropic failure if cause from a broken belt and this thread would not have been made in that case.

Where are you getting your stats? And what chained motors have you worked on?
Nissan and toyota chains rarely have problems. Nissan chains are good for 400,000 miles. Saab chains (older saabs before GM) are good for well past the life of the car. The only maintenance they require is replacing the timing chain tensioner (usually once or twice throughout cars life). and replacing the chain guides (usually once in a cars life). If the chain guides are metal, you wont have to service them at all.
I have not heard of a timing chain detonation, unless something else in the engine failed to cause it, i.e. losing oil pressure.

www.aa1car.com/library/leakdown.htm
What Is An Engine Leakdown Test?
By Larry Carley c2006
A leakdown or cylinder leakage test is similar to a compression test in that it tells you how well your engine's cylinders are sealing. But instead of measuring pressure, it measures pressure loss.
A leak down test requires the removal of