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-   -   Compression test results - diagnostic help please (https://www.miataturbo.net/general-miata-chat-9/compression-test-results-diagnostic-help-please-21823/)

patsmx5 09-20-2008 07:18 PM

No compression= cams not timed properly. You didn't put the timing belt on correctly.

///tonic 09-20-2008 10:43 PM

Everything is lined up per the manual, as best as I'm capable of seeing.
There are 19 belt teeth in between the TDC marks on the cams.

It looks like this:
http://www.rivercityroad.com/garage/pics/bigticks.jpg

patsmx5 09-20-2008 10:54 PM

Did you have the front cylinder (#1) at Top Dead Center when you put the cams there?

///tonic 09-21-2008 10:27 AM

Just pulled valve cover and cam gear cover off and snapped a couple of shots:

With the #1 at TDC per the crank pulley timing mark:

http://tonic.smugmug.com/photos/376951794_QXea2-XL.jpg


My cam gears look like this:

http://tonic.smugmug.com/photos/376950919_9cNd5-XL.jpg

patsmx5 09-21-2008 10:34 AM

First, I think that's the wrong mark on the crankshaft. But nevermind that for now. Pull spark plug #1 and drop a long extension in it so that it sits on the piston and sticks out of the valve cover. Now turn the engine and watch it go up and down. Now use that to put the engine at TDC, and see if your mark is still right, and see if the cams are right. Your balancer could have slipped on you and be throwing off the cam timing.

I'm not sure if 19 teeth between alignment marks is right or not. Also, I can't tell much from your pics. Try putting the camera exactly in front of the gear so we can see if it's actually straight up. From your pics nobody can tell.

///tonic 09-21-2008 10:52 AM

I have already verified that that is the correct mark using a long extension. It's also the only mark on the pulley, and the one that I've used to set the timing on the car in the past.

Sorry the upper radiator hose is in the way. what do you want, a straight on shot of the exhaust camshaft pulley? If I shift the camera three inches to the right, it's still going to look exactly the same.

patsmx5 09-21-2008 11:05 AM

Ok, you say it turns slow AND you have no compression. And you rebuilt your lifters. Did you put clean oil back in the lifters? If they don't have oil in them they will merely collapse and not open the valves. That would explain the no compression and slow spinning. You did something wrong if you have no compression. You gotta figure it out. If you KNOW the cam timing is correct, I'd start checking your lifters.

///tonic 09-21-2008 11:06 AM

Just re-confirmed TDC with the extension method. It's right on. Couple new photos are currently uploading.

///tonic 09-21-2008 11:11 AM

I did put clean oil back in the lifters, but only a small amount so that they were still collapsible under finger pressure. I think that must be the issue.

I did watch the motor crank over with the valve cover off and the valves are actuating, but perhaps not sufficiently?

patsmx5 09-21-2008 11:16 AM

Yeah the lifters are supposed to be soaked in oil during assembly. That's your problem if the cam timing is right.

One thing you could try. Kill fuel and spark to the engine. Unplug the wires that go to the ignition coils. (not the sparkplug wires) and unplug the injectors or pull the fuel pump fuse. Then pull the sparkplugs and spin the motor over for a while. Might get the lifters to pump up. I really have no idea, but it might work.

///tonic 09-21-2008 12:15 PM

Too late. Camshafts are off the car. Going to rebuild the lifters and then re-assemble.

magnamx-5 09-21-2008 12:46 PM

that is alittle extreme man but ok. Be sure to saok them and then prime the oiling system of the car upon reasembly.

///tonic 09-21-2008 02:16 PM

What I'm trying is just submerging the lifters in a cup of oil, and squeezing them repeatedly until I can no longer get any air bubbles out. After, they remain squishable, but become substantially stiffer. Is that going to do it? Or do I need to get that inner plunger full, so that they're totally impossible to compress?

patsmx5 09-21-2008 02:25 PM

You want to fill them with oil. If you try, yeah you can squish the oil out. But don't. Rather get them full and keep them full. Don't lay them on their sides where they could leak out. Hell, keep them submerged in oil till you get ready to install them. I do believe you want all the air out of them.

greddymx5 09-21-2008 05:59 PM

The hydrolic lifters (empty or not) have no effect on compression.
You can check your timing again... The timing mark on the plastic is NOT correct for the alignment of the distribution. Only the crank gear is...

Remove the top plastic cover to see the notch in the gear and then look at your timingwheels. Bet your off...

When reassemling my engine i found the pulley to match up to the 10 degree mark on the plastic cover. Gear at TDC...

If you take your head off the car, remove the cams and hydrolic lifters.
Turn it upside down and fil it up with water.
Let it stay there for 2 hours.
All water should be in there or the valves are not closing.

patsmx5 09-21-2008 06:08 PM


Originally Posted by greddymx5 (Post 310709)
The hydrolic lifters (empty or not) have no effect on compression.

If you take your head off the car, remove the cams and hydrolic lifters.
Turn it upside down and fil it up with water.
Let it stay there for 2 hours.
All water should be in there or the valves are not closing.

Lol. Not very good advice Mr. Sir.

greddymx5 09-21-2008 06:24 PM


Originally Posted by patsmx5 (Post 310714)
Lol. Not very good advice Mr. Sir.

What??

The valves are kept closed by the valve springs, even if there is no oil in the lifters.

Or did you mean the water??
There is nothing wrong with using water to check for leaks. Done it several times with good results.
Of course it is better to pressurize the head, but this is a budget site or am i forgetting anything??

patsmx5 09-21-2008 06:37 PM

Hmm, yeah you're definately missing something. If he wanted to know if his valves were leaking, how much they were leaking, wanted to know immediately, and didn't want to pull the engine apart, he could just do a leakdown test. This would also tell where any leaks are.

And if you had the head off and wanted to check that the valves are sealing properly, there are two or three correct ways to do so. Your method is not one of the correct methods.

greddymx5 09-21-2008 06:56 PM

Thats why it is stated: IF you take your head off the car...

Off course his valves are leaking or do you think all the pistonrings go bad by replacing the head...

And off course there are better ways to check the leakage.
This is a simpel methode everybody could do and tels you if there is a big leakage before placing the head back. (like 0 psi compression)...
Tuners use the same to measure the difference in volume on high hp engines.
(gues they are not using water...)

(helped me find a burned valve before i took out all...)

///tonic 09-21-2008 06:59 PM

Verdict on the lifters after evacuating all air = no change whatsoever. Except now my battery needs another charge.

I'd love to believe greddymx5 that the timing mark is 10 degrees off, but the extension test says otherwise.

I'm just about to give up on this shit.


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