In reply to Olemiss540 :
Doc and you called it.
I did a compression test today.
180
180
180
180
At this point I'm thinking this is too good to be true.
160
100
Whomp whomp.
Is there anything I can learn from doing a leak down?
How awful is pulling the head off in a un air conditioned Texas garage in July and August going to be?
In reply to czerka :
I did the head. Its more tedious than anything. Lifting the head is easy, putting it back carefully is back breaking but doable. I had my wife hold the from while I grabbed it from the side.
The exhaust manifolds can stay on unless you have long tubes. The chain tensioner & chain can be a bit of a pain to hold in place while dropping the head on. It may not be a bad idea to put a straight edge on the head as they tend to warp
Low compression doesn't mean head gasket. If you don't have coolant loss or cooling system overpressurization, you probably don't have a head gasket issue.
Now, on the other hand, stuck/weak rings with a lot of blowby can cause an engine to run hot.
What I'm getting at is, I wouldn't start ripping the head off just for the hell of it.
Pete. (l33t FS) said:Low compression doesn't mean head gasket. If you don't have coolant loss or cooling system overpressurization, you probably don't have a head gasket issue.
Now, on the other hand, stuck/weak rings with a lot of blowby can cause an engine to run hot.
What I'm getting at is, I wouldn't start ripping the head off just for the hell of it.
I can bet you money there is a headgasket issue (albeit very minor), that is causing the increased temps. These engines in particular are increadibly notorious for being susceptible to very minor over heat incidents and I bet once the headgasket is done, OP will no longer have any cooling issues on track at speed.
OP,
I personally felt adding ARP head studs along with a OEM head gasket was a worthy investment (and happened to have an easier torquing sequence along with making sliding the head on easier using them as guides). I actually enjoyed the project and was simple given all of the documentation on the process available on the forums. DONT forget the RTV at the timing cover and anywhere two metal surfaces are bolted together forming a joint.
In reply to Pete. (l33t FS) :
What would I do to diagnose that?
I've recently gone thru the pcv system and it all looked pretty good.
In reply to Olemiss540 :
I'm with you. I looked a bit into it last night and doesn't really seem to be that big of a project. Would you recommend getting the cam locks and vanos tools?
czerka said:What would I do to diagnose that?
I would do a leakdown test before I pulled the head off.
czerka said:In reply to Olemiss540 :
I'm with you. I looked a bit into it last night and doesn't really seem to be that big of a project. Would you recommend getting the cam locks and vanos tools?
Yes to both (or find a loaner program on the forums if possible since many have these sitting on their shelves). And rebuild the vanos if you haven't already.
I agree with OleMiss, that head gasket is gone. It only takes one slight over heating event to cook these. I'd pull the head and take it to a machine shop to make sure the surface isn't warped and that the valve guides are good. Then put it back together with ARP head studs and an OEM gasket.
docwyte said:I agree with OleMiss, that head gasket is gone. It only takes one slight over heating event to cook these. I'd pull the head and take it to a machine shop to make sure the surface isn't warped and that the valve guides are good. Then put it back together with ARP head studs and an OEM gasket.
I agree with Doc.
I would rent a cooling system pressure tester(as an E36 owner(soon to be ex!) I bought one). Helped me diagnose my cracked radiator and later my blown headgasket which were not surprisingly related.
buzzboy said:I would rent a cooling system pressure tester(as an E36 owner(soon to be ex!) I bought one). Helped me diagnose my cracked radiator and later my blown headgasket which were not surprisingly related.
This!!! Pressurize the cooling system and let it set for a good while with the plugs out of the engine. See if you get pressure drop. Then spin the motor over and see if you can see water/coolant being shot out of a plug hole.
A leak down test can tell you if you have a problem with rings or valves.
In reply to dean1484 :
Okay I'll try this. I've pressure tested it before and it either leaked so slow I didn't notice or it didn't leak but I'll try with the plugs out.
I am going to do a leak down test as well.
When I pressurized the cooling system, it leaked more than it has before. I pressurized it to just over 20psi and by the time I found the right size socket to rotate the engine it had fallen to jsut under 19 or so. When I spun the engine, nothing came out of any of the plug holes.
I did couple leak downs, engine was cold. The first time testing cylinders 1 and 2 I used an extension and rotated the engine under I thought I found TDC. All other times I found TDC by hooking the leak down gauges up and rotated until the needle stopped moving.
1- 90/74
2- 90/78
3- 90/85
4- 90/86
5- 90/80
6- 90/40
---------
1- 90/81
2- 90/87
3- 90/86
4- 90/87
5- 90/73
6- 90/52
On all cylinders you could hear air at the oil fill. Wasn't particularly loud, I had to put my ear all the way to the hole. Cylinder 1 was louder than the other 5. I felt a little air at the dip stick, if I covered the hole with a finger it felt like there was pressure. Not much though. I never heard anything at the exhaust. I held the back of my hand up the exhaust, cylinders 5 and 6 felt like there was a little bit of air coming out of them. Not very scientific, but it smelled like there was something coming out. I really couldn't see into the expansion tank since I had it to move it way up out of the way to spin the crank, but I didn't hear anything and I don't know if I would have been any to feel them, but I didn't feel any bubbles when I touched it. I took the air filter off, didn't hear anything at the throttle body.
I was going to put a borescope down into the cylinders but I ran out of time. I'll do it tomorrow.
You'll need to pressurize the cooling system and let it sit overnight. If it has a combustion chamber leak, it will take a lot of time to be noticeable.
In reply to Pete. (l33t FS) :
Oh, dang. I'll have to wait until next weekend to try that.
If it is leaking 1-1.5 psi in 5 minutes or so, won't it just be at 0 in the morning?
Your cooling system is bleeding down 1-2 psi in 5 min? If so chase this down.
Really left field idea but could the head be cracked and it is leaking in to an exhaust port?
Usually if it leaks down that fast and there's no obvious coolant loss, it's a leaky pressure tester. They almost universally suck.
I tried pressurizing the cooling system again. Pressurized to 15psi, within the first couple minutes it dropped to 14 but its been holding at 13.9 for 90 minutes now.
czerka said:I tried pressurizing the cooling system again. Pressurized to 15psi, within the first couple minutes it dropped to 14 but its been holding at 13.9 for 90 minutes now.
It ended up holding 14psi for about 4 hours before I moved stuff around to bore scope the pistons. I left it pressurized, but it'll be next weekend before I can look at it.
I was trying to beat a storm so didn't get the best pictures of the pistons. 5 and 6 look more shiny(or maybe wet?) than the others. Only got shots of the walls on 4-6. I didn't see any scoring or anything but I was moving fast.
I hate to beat a dead horse here, but you need a head gasket. Take the head to a machine shop to make sure it isn't cracked or warped or needs valve seals. Reassemble with ARP head studs and an OEM gasket.
The other thing I have done (but this is far from a correct test) is to pressurize a cylinder with shop air and put a gauge on the coolant side of things. Let it sit at 125-130 psi for an unspecified amount of time. Maybe an hour maybe 4 hours per cylinder? And see if pressure goes up in the coolant.
But with those low comp numbers and you saying it is leaking out in to the case I would bet your motor is toast. Doing a head on a motor that has that much blow by in to the case is a wast of $$$. I would be looking for a known good replacement motor or rebuild the one you got. I would not be surprised if you find multiple problems.
That motor is telling you it is in need of help. A head gasket and a re done head will just be a bandaid for what is really a motor that needs a rebuild.
EDIT. Obvious you want to make sure the motor can not turn over when doing the test I noted above.
docwyte said:I hate to beat a dead horse here, but you need a head gasket. Take the head to a machine shop to make sure it isn't cracked or warped or needs valve seals. Reassemble with ARP head studs and an OEM gasket.
While I agree there's a 90% chance this is the correct answer, that leaves a 10% chance that you pull the head off and there's no smoking gun -- everything looks fine. In that case you'll really wish you'd done all these easy/free tests before taking it apart, because there's no way to do them once the head is on the bench and you're left with the question of "what now?" BTDT.
In reply to codrus (Forum Supporter) :
That's a concise way of putting what I felt by instinct and couldn't bring to my forebrain.
Plus, if it still runs hot, now you have the added question of "did I torque it properly?" "Was the deck scratched?" "Was the block warped and I missed it?" etc.
An aside, I am a little lost that 235 is high for an iron block engine, given how HOT they run the newer engines. OTOH I also don't have the direct experience with them to know what hurts them, so I'll defer to those that do.
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