did a compression test

[supra90turbo]

and it went better than i expected it to go.

1=155
2=155
3=160
4=160
5=155
6=160

not bad at all as far as i'm concerned.
now, even when it's got good compression, i believe i should do a leakdown, since my overflow will puke still, and my upper hose will get pressurized...
my pcv catch can is full of condensation and all oil in the pcv track is that white oil/water mix gross shit.
and not only that... i still have oil in my accordian and ic pipes, but it could be from my old pcv oil, even though i cleaned it out...

i need to buy a leakdown tester.... like yesterday.

 

[supra90turbo]

um... nobody? someone's gotta know something about the many different leaks a headgasket can have.

 

[siman]

Have your rebuilt the motor?

If your compression is pretty equal across the board I dont think you have a BHG...if thats what your aiming at?

As for the coolant pipe being pressurized....thats totally normal, as well as the overflow....you might just have too much coolant in the system....I did that once accidentally.

-Jonathan

 

[lagged]

if you have oil/water mixing in the PCV lines id say its probably a BHG. thats what mine did. the number 6 water jacket blew out away from the bore. no oil on the dipstick, but a nasty thick oil and water milkshake clogging up the PCV lines.

pressure test the radiator/cooling system. that will tell you for sure.

and i have been told by many that that type of BHG is caused by detonation.

 

[Orion ZyGarian]

Those are some ideal PERFECT compression numbers man...awesome, passed with an A+ I'd say!!

I too am paranoid about having a possible BHG even with my 80ft lbs MHG, but compression would be really bad with one (or more) of the cylinders and you'd have a noticable loss of power...which I dont have and obviously you dont.

Good luck!

 

[CPT Furious]

Might not be bad to do an engine block test to see if you have exhaust gasses in the coolant just to be sure!

 

[lagged]

the reason i think it could STILL be a BHG is if the HG leaks only intermittantly...as mine did.

 

[John Lunsford]

I hate to say it but thats a leaking head gasket. You can have perfect compression and no leaks or problems at idle and the gasket will still leak under boost. What happens is that when the block or head is milled or anything, sometimes there are grooves that go from the cylinder to the coolant passage. These will seal until the compression goes way up, like under boost. When this happens, compression makes it's way from the cylinder to the coolant passage and pressurizes the coolant, which in turn pushes coolant out of the overflow. It only does it under boost so at idle your compression will be fine and there will be no problems apparent. I'd bet that's your problem. I've seen it 20 times at least around here. One thing's for sure, if there's coolant on the intercooler from the overflow, it's a leaking or blown headgasket everytime, no exceptions unless your radiator cap or thermostat is faulty.

 

[supra90turbo]

damnit.
lol


yep, john, this is exactly what's happening.
i have a new rad cap and thermostat, so it must be the headgasket.
and its probably from detonation. which sucks.
so, since i've only got ~20k mi on this headgasket, i may be able to clean up the head surface and put a new headgasket on... i'll check all dimensions with a machinists straightedge and so forth, clean it up real good, have the head planed if necessary, and this time use some mopar headgasket coating on the new mhg. or shall i step backwards and use a factory headgasket... i DO have ARP headbolts but, i really dont like the idea of putting a factory headgasket on...

maybe i'll just rebuild the sucka...
JE's...
shot peened rods...
knife edged crank...




uh oh.......

 

[TONY!]

I hate to say it but thats a leaking head gasket. You can have perfect compression and no leaks or problems at idle and the gasket will still leak under boost. What happens is that when the block or head is milled or anything, sometimes there are grooves that go from the cylinder to the coolant passage. These will seal until the compression goes way up, like under boost. When this happens, compression makes it's way from the cylinder to the coolant passage and pressurizes the coolant, which in turn pushes coolant out of the overflow. It only does it under boost so at idle your compression will be fine and there will be no problems apparent. I'd bet that's your problem. I've seen it 20 times at least around here. One thing's for sure, if there's coolant on the intercooler from the overflow, it's a leaking or blown headgasket everytime, no exceptions unless your radiator cap or thermostat is faulty.

Thank you very much!! I have been trying to tell that to the SF members for some time, and here at SM also. I call it an intermitten BHG in my write up:
http://supramania.com/forums/showthread.php?t=251
and just yesterday I almost snapped on a guy on SF because I thought he was suggesting that a compression test was the way to find out if a BHG was present:
http://supraforums.com/forum/showthread.php?t=297001
Highlights of that thread for those who don't have SF accounts:

And why did you do a compression test?
What were you looking to determine?
A BHG? Checking for ring/piston wear? Valve wear?

What are you trying to find with your test?

If you were looking to see if you have a BHG (which you did not state), you picked the wrong test/way of diagnosing. You did mention however, that you think the results mean that you don't have one.

Everyone on SF thinks that a compression test is your best answer in seeing if you have a BHG -- it only is if the HG is long gone...

The thing is, many people as I keep reading, think that a compression test is the way to see if you have a BHG. My car had a BGH and the numbers came out fine. Compression tests don't show BHG's in their beginning stages -- when you should know about them, not later on.

Also, the thing I don't like about compression tests is that you get numbers, but not necessarily know what they mean sometimes. You could have a small leak/wear (not necessarily only a BHG type leak, but also another type) that will decrease your pressure; but then have some carbon build-up that will increase your pressure. So you can have two problems making you think you have a healthy engine, when you really don't. I had such an experience.

A leak down test is a better test many times for assessing an engine, and you will see/hear/feel where you are leaking.

BHG testing (coolant to water jacket type): get a block tester -- if you have already checked for the other possible problems that can cause overheating/coolant loss.

If you wanted further analysis with a compression test, do a wet/dry compression test. You already have the dry numbers, get the wet ones (with oil put in the cylinders)....

...As far as the variations you got so far (compression test), there can be a couple of reasons.
Maybe you have carbon build-up on the high cylinders; the power of the battery can also have an effect (if it is weak) and give an overall low reading for all, I'm sure there are other reasons that can also give an off reading. If you wanted to do a leak down test, it is linked within my write-up:
http://supramania.com/forums/showthread.php?t=2229

Well this post gives more info on tests, and I will probably refer to it in the future as well.

 

[John Lunsford]

damnit.
lol


yep, john, this is exactly what's happening.
i have a new rad cap and thermostat, so it must be the headgasket.
and its probably from detonation. which sucks.
so, since i've only got ~20k mi on this headgasket, i may be able to clean up the head surface and put a new headgasket on... i'll check all dimensions with a machinists straightedge and so forth, clean it up real good, have the head planed if necessary, and this time use some mopar headgasket coating on the new mhg. or shall i step backwards and use a factory headgasket... i DO have ARP headbolts but, i really dont like the idea of putting a factory headgasket on...

maybe i'll just rebuild the sucka...
JE's...
shot peened rods...
knife edged crank...




uh oh.......

My advise to you would be to get a Greddy (I like the design better) metal gasket and make sure that the surfaces are smooth and completely free of the little grooves left from the machining. Do not put any kind of coating or spray treatment on a metal head gasket. If you are reusing a metal head gasket, all you have to do is drill out the brads that hold the layers together and clean the layers thoroughly. I use a wire wheel brush on my grinder, but you really have to be careful so that it don't grab it and ruin it.
More info here... http://www.jblmk3.com/id109.htm

 

[supra90turbo]

thanks again, john!

however, i may need more info on lapping. i always read about it, saw what it did, but i dont believe i'm exactly sure what it is and how it's done....

 

[souprat]

yeah i'll just say my compression was 180,180, 179, 182, 180 and 180. cracked that sucker open and and guess what, bhg in the #1 and #6 cylenders. just a slight bhg, but a bhg none the less.

 

[siman]

on a MHG? :icon_conf

 

[Adjuster]

I agree with everything about the compression check missing the mark, and the reason many MHG leak. (Small machine marks, and scratches)

I also know that the brake quiet, and some other coatings you spray on the MHG before you install it work very well at sealing up those small scratches for the most part. (One old dog I talked to about this swore that aluminum paint is the best head gasket coating he knows of. Says he has built thousands of motors, and he sprays all the head gaskets with aluminum paint, then while it's tacky, set's the gasket in place and bolts on the head. the paint fills in any voids, and seals up the gasket.)

Makes sense to me, and it's a no downside proceedure. It will not clog up your cooling system. or cause oil problems. It does not foul your plugs. So why not coat your MHG before you put it in place? I see no downside, and have it on my own car, so far, so good. (And a few others, with no problems on them either.)

 

[siman]

I coated mine with a copper spray adheasive. worked like a charm...hung the HKS MHG up by a unwound coat hanger in the garage and sprayed away :icon_razz

I mean heck, you put gasket SEAL on the other gaskets on and around the motor....why not gasket SEAL the HEAD GASKET?....it just makes sense :icon_bigg

-Jonathan

 

[Xtreme]

I agree, I put copper spray on mine, and it stuck like glue. Good stuff, imo.

 

[siman]

I agree, I put copper spray on mine, and it stuck like glue. Good stuff, imo.

yeah :naughty: .......it was pretty too....it was all sparkly! :greddy:

 

[John Lunsford]

Well guys, you do what you want with the coatings but you don't need it if the surfaces are done right. There is a downside to it in some cases. I know of at least two motors that had to be torn down because of that crap clogging things up. When you sandwich that stuff between stainless steel, iron and aluminum, ANYTHING you put between them will be squeezed out unless it's as hard as they are. It may fill in the voids that shouldn't be there, but it will also get in your oil and coolant but it's up to you, just remember that because several others do it and don't have problems it don't mean that it will always work and if I've seen even one that had to be rebuilt because of it, that would be enough for me especially when it is totally unnecessary.
When there are scratches or milling marks that go from the combustion chamber to the coolant passage it's like a tunnel. The stainless steel gasket will not fill it, nor will the iron block or aluminum head give to the gasket to block it off. You can fill it with a spray on material, but in time it WILL push out and there you'll be. Every time your car detonates it's like a hammer pounding away at the material in that tunnel and you can bet that in time it will break through leaving you right back where you started. The ONLY permanent remedy is not to have the "tunnel" there in the first place.
I've been there and done that many times and I've learned through experience.

 

[Idealsupra]

Well guys, you do what you want with the coatings but you don't need it if the surfaces are done right. There is a downside to it in some cases. I know of at least two motors that had to be torn down because of that crap clogging things up. When you sandwich that stuff between stainless steel, iron and aluminum, ANYTHING you put between them will be squeezed out unless it's as hard as they are. It may fill in the voids that shouldn't be there, but it will also get in your oil and coolant but it's up to you, just remember that because several others do it and don't have problems it don't mean that it will always work and if I've seen even one that had to be rebuilt because of it, that would be enough for me especially when it is totally unnecessary.
When there are scratches or milling marks that go from the combustion chamber to the coolant passage it's like a tunnel. The stainless steel gasket will not fill it, nor will the iron block or aluminum head give to the gasket to block it off. You can fill it with a spray on material, but in time it WILL push out and there you'll be. Every time your car detonates it's like a hammer pounding away at the material in that tunnel and you can bet that in time it will break through leaving you right back where you started. The ONLY permanent remedy is not to have the "tunnel" there in the first place.
I've been there and done that many times and I've learned through experience.

john i just have to say...i 100% agree with you on the copper or whatnot coatings... i PERSONALLY lost a hg due to copper coating... and i have seen it on other engines as well..

i have since been saying over and over to NOT use it and have things done right and you dont need it...and all i usually get is criticism and non-believers...