Compression Y U NO MAKE SENSE?

[mzspeed14.0]

Hello friends, I'd like to start by saying I need to buy everyone here a beer cause you all have been very helpful over the years.

Today's Episode: Compression

I did a dry and wet test, below are the numbers:

Dry: 200/140/168/176

Wet: 215/150/192/192

I know 180ish across the board is where I should be.
I know that 28psi is the max variance.

Symptom: Coolant boils out of overflow reservoir.

Still runs and idles okay.

Is it my head gasket? Piston ring?
Will my (built) bottom end be alright?
What else could it be?
What's it gonna cost?
Why is my demeanor directly proportional to the running condition of my car?

Thanks again for your support and expertise!
-Ryan

 

[Protege03ak46]

What brand of tester? How did you conduct the test?

 

[Dpwhitehead1]

just looking at the numbers, makes me think piston rings.. to see if it's a head gasket, do a leakdown test. they are very cheap and will tell if there's any exhaust getting into the coolant. try that.

 

[mzspeed14.0]

Actron Tester. It's a cheapo but I figured it could confirm variances between cylinders. Here's a link to the tester I used.

My test procedure:
Remove spark plugs and injector fuse.
Test each cylinder (wet and dry). Wide open throttle.
Each test was 5 seconds

Let me know what you think.

 

[mzspeed14.0]

just looking at the numbers, makes me think piston rings.. to see if it's a head gasket, do a leakdown test. they are very cheap and will tell if there's any exhaust getting into the coolant. try that.

That's next on the list. Is is possible for that test to not detect a head gasket leak? I don't see any bubbles with the radiator cap removed. No sketchy residue under my oil cap...

Thanks for the quick replies

 

[Protege03ak46]

Well, cheap testers pretty in accurate. I've done a side by side comparison of a cheap and higher quality snap-on. The Cheap one was consistantly +/- almost 20 psi. Now, I'm not saying that the tester is the problem, but it could be a factor. If it was a head gasket, you'd have white smoke atleast during warm-up. Rings youd have a blue-ish tint to your exhaust vapor. Leaky valves could be a possibility. I would definitely do a leak down test ASAP. When you do it, pop your radiator cap and hope for no bubbles..

Edit: also during the leak down, pop the intake and listen for leakage from the valves. You'll be able to do the same for exhaust...

 

[BRIAN_MP5T]

It could simply be a head gasket

Or the head could be warped causing the same symptoms as the bad head gasket

Does the coolant smell a bit like gas?

 

[Dpwhitehead1]

That's next on the list. Is is possible for that test to not detect a head gasket leak? I don't see any bubbles with the radiator cap removed. No sketchy residue under my oil cap...

Thanks for the quick replies

the leak down requires you "i think", to let the car warm/rev it.. so idk.

 

[Protege03ak46]

Here you go, good read
http://www.carcraft.com/techarticles/116_0406_cylinder_leakdown_tester/viewall.html

 

[mzspeed14.0]

Does the coolant smell a bit like gas?

The coolant does smell a bit like gas.. Head?.

It doesn't look like there's oil in it though.

 

[BRIAN_MP5T]

If the coolant smells like gas, it's probably simply a head gasket

The gasket is under $100 but it is a bit intensive to get at it

Do not reuse the head bolts they are $100 as well

 

[Dpwhitehead1]

If the coolant smells like gas, it's probably simply a head gasket

The gasket is under $100 but it is a bit intensive to get at it

Do not reuse the head bolts they are $100 as well

you can re use head bolts. they cannot be longer than 4.153 in. direct from the mazda factory manual.

 

[mzspeed14.0]

Do we have a how to (with torque specs, detailed pics, etc) on replacing a head gasket?

I'm thinking about replacing the entire head.. What do you guys think about THIS?

May as well replace the rear motor mount while I have the head off..

Parts list:
Ebay Head: 380
Arp Studs: 120
Cometic HG: 100
Rear MM: 100
Total 700+ a weekend

 

[mzspeed14.0]

Hmmm. I already have ARP head studs. I've been reading that it's okay to reuse 'em. What do you think?

 

[Dpwhitehead1]

Do we have a how to (with torque specs, detailed pics, etc) on replacing a head gasket?

I'm thinking about replacing the entire head.. What do you guys think about THIS?

May as well replace the rear motor mount while I have the head off..

Parts list:
Ebay Head: 380
Arp Studs: 120
Cometic HG: 100
Rear MM: 100
Total 700+ a weekend

the flopical or w/e website has the service manual. that has all the specs and stuff.
cam cap bolts are 100inlbs and the head bolts are 16.5 ft lbs +90* +90*

 

[f1yen]

Have you checked your thermostat? I had one of those "fail safe" ones and It let the car run okay.... but would go on and off and I was also boiling coolant in my reservoir. but that was when my temp gauge was also high.... It must have failed/partially failed because a quick replacement with a non-failsafe one fixed the problem.

 

[dacquesta1]

your compression variation between cylinder 1 and 2 is most likely the head gasket or possibly a warped head as brian suggested. if i were you i would pull the head, have it milled and replace your water pump, timing tensioner, timing idler, timing belt, timing tensioner spring and your cam seals.

 

[mzspeed14.0]

It was the HG. Resurfaced the head and did all the timing goodies while I was at it. Even the rear motor mount.. So, reliability has been restored. Still runs like poop when it's up to temp and in boost. I'm thinking a sensor it making it angry.. I know it's not the WG.. Thoughts?