MS6 Low compression and Timing?

A

AnM23

Greenie N00B Member
Hey Guys,

I am new here and I am having a few Issues with a 2006 MS6 2.3 Turbo. So I will start with what I noticed. When I turn the car over it takes a super long time to get it fire and run. Once its running it sounds decent.
But I couldn't get it to just turn over like it should.

So I decided to run a compression check. Wet and Dry. First I did the dry test.

Numbers came out like this :90-60-60-90

After performing a wet only cylinder 1 came up very slightly. The rest stayed the same.

I wasn't sure the compression tester was working correctly so I performed another one and the test results were exactly the same.


Prior to this I inspected the timing chain and marked a few links and teeth with a paint pin. After checking when the valve cover was off I noticed they no longer match at all. Valve cover also has some chain slack or slap damage from it at some point contacting the valve cover.

I have set the crank shaft to TDC with m6 bolt and the tool in the blind plug. both cylinder 1 came lobs facing each other.


I don't want to just replace all the timing and VVT if the compression issues aren't related to the timing.

So my next test I feel like should a leak down test and see what happens. Does any one else have any ideas or opinions. I am not as familiar with the common or known issues of these motors

Kinda find it odd the 1 and 4 have 90 and 2 and 3 have the exact same regardless of wet or dry test.

Thanks and I appreciate it.
 
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I've seen valves caked in carbon so bad they didn't close and injectors leaking causing low compression. Wild shit.

Compression is horrible tho. And vvt sounds bad. Time to tear into it
 
Yea I was afraid of that. I did spin the motor twice clockwise and made sure the VVT notches lined up. but whos to say.
my worst fear is I have a warped head/cracked. I just found it a little odd the adjacent cylinders 2 and 3 are the exact same and 1 and 4 are as well.
 
So I did a leak down test and it was are garbage. I then pulled the intake off sprayed some stuff down the intake valves and every one of the intake valves shoots out out the fluid like crazy none of them seal properly.
 
You could have bent valves if the timing jumped. My suggestion is to buy another engine to keep the car on the road for now then tear down the old one to see if it's salvageable.

You could also remove the camshafts and perform the leak down again. All the valves would be closed so if any cylinder has a ton of leak down you know the valves are bent.
 
I removed the cams and and performed a leak down test and every single intake valve was leaking major air. So I pulled all the valves and I couldn't believe the amount of carbon build up around the valve guides. Overlapping with carbon. breaking the entire head down now.

Raider said:
I've seen valves caked in carbon so bad they didn't close and injectors leaking causing low compression. Wild shit.

Compression is horrible tho. And vvt sounds bad. Time to tear into it
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removed the cams and and performed a leak down test and every single intake valve was leaking major air. So I pulled all the valves and I couldn't believe the amount of carbon build up around the valve guides. Overlapping with carbon. breaking the entire head down now.

good call Raider.

Now would you suggest replacing every thing? or can every thing be cleaned up and new valves, guides and relapped? along with timing components. No valves were bent just nasty.
 
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Intake manifold removal would have been easier but you've gone pretty far. I'm kind of stunned as far as how much you tore into it. I think now would be a good time for gearheads like @Enki to give some tips.
 
You can reuse all of the parts but you will need to measure the clearance on the lifter buckets and likely need to swap them around and get some different ones to get everything in spec.
 
JohnnyTightlips said:
These might help you out. When I did my stuff I used MAHLE valve stem seals from rock auto without issue, they were a lot cheaper than OEM.

https://mazdaspeeds.org/index.php?threads/setting-bucket-and-valve-lash-madness-ensues.8721/
https://mazdaspeeds.org/index.php?threads/installing-valve-springs-head-off-the-car.8711/
https://mazdaspeeds.org/index.php?threads/cleaning-valves-outside-the-head.8720/
https://mazdaspeeds.org/index.php?threads/lap-valves-valve-lapping.8710/
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Thanks man those were useful. This car has been a little challenging but now that I am familiar with it, It hasn't been so bad. But every time I fix one thing another issue shows up.
 
Easter Bunny said:
You can reuse all of the parts but you will need to measure the clearance on the lifter buckets and likely need to swap them around and get some different ones to get everything in spec.
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As long as he didn't get the ones in there out of order he should be fine?
 
They wear from use and get out of spec you can reuse them in the spot they were but the correct way would be to get new ones that bring the gap back into spec.

If you are doing any valve lapping or work on the valve seats you definitely need to remeasure and replace.

For a while there was a box of used tappets getting passed around to people building emgines
 
Easter Bunny said:
They wear from use and get out of spec you can reuse them in the spot they were but the correct way would be to get new ones that bring the gap back into spec.

If you are doing any valve lapping or work on the valve seats you definitely need to remeasure and replace.

For a while there was a box of used tappets getting passed around to people building emgines
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Aren't they a wear in part though? I don't think you should use used ones.
 
chad said:
Aren't they a wear in part though? I don't think you should use used ones.
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The lifters aren't really a wear item. I've seen most DOHC lifters be good for hundreds of thousands of miles. It's only when there is either an aggressive camshaft and/or improper lash settings that cause them to fail prematurely. If they weren't reinstalled in the same spot they will need to have their clearances checked.

Side note: are our lifters SUB (Shim Under Bucket)?
 
chad said:
Aren't they a wear in part though? I don't think you should use used ones.
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They are a wear item in that they get thinner not that they go bad. You can buy them brand new in many different thicknesses so there is no harm in using an old one that has worn a bit.

You need to measure them and inspect them of course before reusing
 
L337TurboZ said:
The lifters aren't really a wear item. I've seen most DOHC lifters be good for hundreds of thousands of miles. It's only when there is either an aggressive camshaft and/or improper lash settings that cause them to fail prematurely. If they weren't reinstalled in the same spot they will need to have their clearances checked.

Side note: are our lifters SUB (Shim Under Bucket)?
Click to expand...
You have to buy them in the size you want, they are not shimmable which sucks. I measured all of the buckets coming out of my head that had 155k miles on it and they all exactly matched the sizing that was stamped on them. The reason you need to check them is because the valve and valve seat can wear over time. You will also make them out of spec when you reseat the valves as you are essentially sanding and mating the valves to the head to remove material "which changes the valve length". I bought the buckets used in the focus or mustang or something. They talk about it in here https://corksport.com/support/instructions/GEN-6-501-WEB.pdf it is cheaper to get those vs the mazda ones.
 
L337TurboZ said:
The lifters aren't really a wear item. I've seen most DOHC lifters be good for hundreds of thousands of miles. It's only when there is either an aggressive camshaft and/or improper lash settings that cause them to fail prematurely. If they weren't reinstalled in the same spot they will need to have their clearances checked.

Side note: are our lifters SUB (Shim Under Bucket)?
Click to expand...
What I mean when I say wear in is the cam lobe and the face of the tappet matching. I read that somewhere a while ago.
 
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