engine and drivetrain M10 Headgasket leak

[318Turbo]

Hello fellow members,

 

I hope that someone might be able to help me.

 

My 1.8 M10 enigne blew the headgasket  a while back. I removed the head, had it pressure tested and the engineering shop gave it a slight skim just to be sure that it is straight.

 

I cleaned the block surface and then fitted a new standard gasket.

 

I am using ARP head studs and so I torqued the head down in three stages (correct sequence) to a final reading of 80 ft lb (110 N/m). ARP specifies 90 ft lb for the studs that they supply on the M10 engine but I decided to do 80 as 90 seemed to be a bit much. I did not re-torque afterwards as ARP says that it is not necessary.

 

After the first warm up and dyno session all seemed to be fine. However yesterday when I was working on the car I saw that there was coolant on the engine block from the head/head gasket area. This was under the intake manifold side. There were also water on the exhasust manifold side but I assume that this could be due to some of the coolant making its way to the other side as the motor is tilted...?

 

There is no water in the oil and compression on all 4 cylinders are spot-on equal.

 

Do I need to re-torque? Is the torque spec from ARP too much for a standard gasket and maybe I caused some damage leading to a leak...?

 

Can anybody shed some light on this please? Any help will be much appreciated.

 

Thanks

 

Thomas

[Tommy]

I would still try to find the leak elsewhere than head gasket. It's not common that head gasket leaks coolant out from the engine but not into oil or combustion chamber.

The divider part next to intake manifold would an obvious place - you know the part where upper coolant hoses connect.

 

  Tommy

[Stevenc22]

I agree. After my head gasket replacement it took me a few weeks to stop various leaks from the different coolant hoses you just disturbed.

[KFunk]

I'm using a slightly thicker stock style headgasket, and torqued the ARPs to 90 ft. lbs., and have had no problems with it in a couple years.  A bit scary to torque that high, but it doesn't take much turning to get it to click once they're that tight.  There's no real stretching/squeezing to do.

 

Anyways, I'd bet your leak is elsewhere like others said.  Check all hose clamps and stuff for tightness. 

[Preyupy]

You spent the money to buy ARP studs (arguably the best specialty automotive fastener manufacturer out there) and then not use their specification for torque?  Go on their site and read the description of how fasteners work and why fastener torque is important.   As for a water leak on the intake side of the engine make sure the water outlet/#1intake manifold gasket is not leaking.  Very often there is a slight difference in thickness of the water outlet flange and the intake manifold flange,  when you torque the fastener that is common to both of them it is very easy to clamp down on the intake manifold and hot the water outlet.   

[remout]

Experts, could this be due to the upper timing cover not being "skimmed" also. Would the cover stop the head from fully seating?

[KFunk]

You should be installing the upper cover after the head is on and torqued down (at least that's what I do).  The little bit of force used to tighten the cover better not be enough to overpower the clamping force of the headbolts. 

[TobyB]

No, the upper timing cover will leak oil, not coolant.

 

And yes, the upper cover CAN wedge the front edge of the head up if you do it wrong, believe it or not.

The power of a clamping interface is not to be taken lightly...  hee hee....

 

I did have one head gasket fail externally- when removed, it was an aftermarket

gasket that had become very brittle, and it simply cracked out a chunk.  After 20 years.

 

t

[Buckeye]

Not sure what brand head gasket you used for the job and did it come with torque procedure or not, but I can tell you in my case I followed gasket manufacture procedure, which was exact as BMW Service Information procedure and did not have any leak issue what so ever the second time. I know old prodecdure is to torque the head in three sequential steps and revisit after 600 mile. But gasket material and technology have changed in the last 40 years.

 

http://www.bmw2002faq.com/topic/121366-cylinder-head-oil-leak/  

 

Also revisit water didvider connection to intake mainfold and ensure water divider is seated properly and watch washer with cut-off edge is seated properly.

 

[318Turbo]

Thanks for all the replies guys. I really appreciate it.

 

I checked yesterday afternoon and I was hoping to find the leak by the coolant neck but it is def dry.

The timing cover was bolted to the head when it was skimmed to make sure that all surfaces would line up.

I used an aftermarket gasket (PAYEN) as BMW South Africa did not have any stock. These engines are not very popular here and this was the best I could buy at the time. The gasket did not come with any instructions so I tightened the nuts down in three steps. 40, 80, 110 n/m (30, 60, 80 ft lbs)

 

I managed to take a photo of where the leak is. This is on the no.3 cylinder.

 

 

I am no expert but it does look as if it could be leaking straight from the hole in the gasket where the coolant flows between the head and block....?

 

[Tommy]

Well there's your leak alright. Now I don't see other chance but to take the head off and see what's wrong. Is there some damage on the gasket or block surface or worst case cracked block.

 

   Tommy

[318Turbo]

You are 100% right Tommy, I will have to take the head off.

 

I can try to retorque just to make sure but in the end I don't think it is worth it.

Before I installed the gasket I cleaned the block surface. Also I checked thourougly for any evidence of cracks before I put the new gasket on. I could not physically see any cracks.

 

This is not a common place for the blocks to crack is it? From what I have found out these blocks normally crack on the bolt holes when not properly cleaned before installing head bolts?

[Roland]

You are 100% right Tommy, I will have to take the head off.

 

I can try to retorque just to make sure but in the end I don't think it is worth it.

Before I installed the gasket I cleaned the block surface. Also I checked thourougly for any evidence of cracks before I put the new gasket on. I could not physically see any cracks.

 

This is not a common place for the blocks to crack is it? From what I have found out these blocks normally crack on the bolt holes when not properly cleaned before installing head bolts?

 

 

Although possible, it is highly improbable that you have a cracked block.  It is far more likely that you have a defective gasket, a warped head and/or fasteners that are improperly fastened.

 

I am unfamiliar with your gasket brand; however, for all I know,  it is a rebranded version of the same gasket commonly available at certain dealers.  Bear in mind that a gasket is designed to bridge any irregularities between the two dissimilar mating surfaces.  If the gasket was mishandled (even unbeknownst to you) it may have been destined to fail.

 

You mention that the head was resurfaced.  But you did not mention  the surface finish.  Often head gasket manufacturers recommend a specific "Ra" or roughness average.  Cast iron heads typically require a slightly rougher Ra than aluminum alloy heads.  Not unlike Goldilocks, too rough or too smooth may lead to a sealing problem.  A decent machine shop should be on top of this.  Parenthetically, it is hard to gauge any margin of error since I have seen many "hand finished" surfaces that have lasted for decades.  Nevertheless, there is some science behind the recommendations and deviation may court failure. http://www.enginebuildermag.com/2007/06/common-mistakes-to-avoid-when-resurfacing-cylinder-heads-blocks/  

 

Another possible issue is your fasteners and the torquing process.  Unless you are using an old-style beam-type torque wrench, it may be that your wrench is inaccurate and out of calibration.  I recall seeing a friend rebuilding an engine and using his click style torque wrench to remove and install nuts and bolts  The engine had been previously "rebuilt" only two years earlier.  It turned out that a 100 ft./lb setting actually measured 70 ft/lbs.  You do the math.

 

You also mentioned using ARP studs.  I am assuming you followed ARP's recommendations  regarding any thread locker on the studs and any lubricant on the nuts.   My uneducated guess is that your 80 ft/lb torque is within the margin of error, but it is better practice to follow ARP's recommendations.  I seriously doubt there is any harm in torquing the head nuts to a fourth stage of 90 ft/lbs.  If these were head bolts, I might be inclined to slightly loosen each nut prior to re-torquing (as described in the shop manual).  Because you are using a different type of fastener, you might want to consult with ARP regarding their recommended "re-torque" procedure.  

 

You also mentioned using a dynamometer without describing the process.  Repeated dyno runs often reveal cooling system shortcomings.  Even if normal care is exercised,  it is not uncommon for the engine to push the heat level after several hard runs.  In other words, you may have unwittingly cooked the engine to the point of causing either a head gasket failure or slight head warpage, irrespective of gasket quality, head work or fastener torque.  I am not saying this happened.  Instead I am merely posing the possiblity.

 

One last thing.  Most gasket manufacturers recommend surfaces being extremely clean and dry for installation.  Were your surfaces super clean and dry, prior to installation?  There is a divergence of opinion regarding the use of gasket sealants.  If I were performing a field repair, literally popping in a new head gasket to correct a leak similar to your symptoms, I might be inclined to coat the gasket with copper gasket adhesive.

 

Fingers crossed.

 

[TobyB]

Huh.  That's right where mine failed, too.

 

My vote is for a piece of crap that held the gasket up enough to make it leak.

It doesn't take much, really.  One grain of sand or wire strand from an electrical

project can do it.

 

He says, having had that happen...

 

t

[318Turbo]

Hello all,

 

Sorry for digging up my old thread. I just thought that I should let you all know what happened further.

 

I obviously ended up taking off the cylinder head expecting to see either a cracked block or head. But luckily it was not the case. So the next step was to check the "flatness" of the surfaces. I bought a new straight edge and checked both the block and head surfaces. They were both within spec so I went a step further and checked again at half the recommended spec. Again perfect.

 

So all that was left to do was to clean the surfaces and fit a new gasket. This time round I used a Victor Reinz gasket as I have done previously. After the first warm up I let it cool down and then gave the ARP's a retorque.

 

So far so good. No more leaks. The car has seen a full dyno session and all seems to be well.

 

In the end it seems to have been a mysterious problem.

 

Thanks again for all the help.