M42 Head Gasket Blown, Project Thread

[bmwman91]

This will be my project log + my questions thread that I document as I sort things out. It may well be a couple of months from now until it's finished.

It looks like it is time for more M42 wrenching. Other than replacing the crank damper wheel and some miscellaneous stuff around there earlier in the year, I have not had to touch this engine since ~2013. Some of you will recall that I had Metric Mechanic build me a 2.1L stroker, which at the time had a couple of valve spring failures, so I had the head off and replaced the HG back then. Maybe I messed something up then, or maybe when the crank damper was coming apart and the timing was way off some of the resulting detonations damaged it, or maybe it is just the result of me driving the living shit out of it lol. Whatever the case, I am 95% sure that the HG is toast between cylinders 2 & 3.

I got a loaner compression test set from the local parts store and saw:
Cyl 1: 70 PSI
Cyl 2: 0 PSI
Cyl 3: 0 PSI
Cyl 4: 50 PSI

This was on a luke-warm engine with a loaner gauge that was probably abused, so I am not really super concerned about #1 and #4. The fitting for the spark plug holes could only be tightened down onto the o-ring with the hose coming off of it, so there was probably just a ton of leakage. Anyway, given that two adjacent cylinders have no compression and I can basically hear air exchanging between them if I put the shop vac onto one spark plug hole, I am assuming that the web in the HG between these went out. I was maybe a mile from home on the expressway when I noticed that the car would not make more power when I got onto the throttle, and I thought that I heard some pinging or other not-good noise for a few seconds before it just kind of ran poorly. I got it home and it certainly seemed to not be running on all cylinders, as well as intake+exhaust notes which sounded like air moving to wrong places at the wrong times. My very first thought was that I got bad gas since this all started about 2 minutes after refueling.

As far as I can tell, the oil is not milky. It's pretty clean since I just changed it 1500 miles ago, which at first made me think it was contaminated, but I think I was just being paranoid. Also, the coolant level in the expansion tank was not altered, so exhaust products don't seem to be making their way into the cooling system. Anyway, how long do you usually find that it takes to turn the oil noticeably milky when a HG is going? I suppose it varies depending on the severity. If I am having this hard a time telling, then either no coolant got in, or I caught it early. I'll drain the oil anyway just to make sure later on in this project.

The M42 HG is pretty straightforward to swap, assuming it is the only casualty there. I am going to have the head milled, but I am also going to check with MM about some newer cams. Apparently a few years after my build, they came up with a new cam profile which boosts top end power 10-15HP, with minimal loss in the mid-range. Maybe I will send them the head for a little refresh and new cams while I am at it. If not, then I will just do it locally since there are competent head machining shops in the area. Decisions, decisions.

So far, here is a list of what all I am replacing as part of the project:
Head Gasket (OEM metal M44, probably)
Head bolts
Inner profile gasket
Outer profile gasket
Upper timing case cover gasket set
Thermostat housing gasket
Thermostat o-ring
TB gaskets
Lower intake manifold gasket
Upper intake manifold gasket
Exhaust manifold gaskets (head and cat pipe)
Rubber exhaust hangers
Engine-to-chassis ground strap
Alternator-to-engine ground strap
Hood-to-chassis ground strap
Spark plugs (all)
Ignition coils (all)

Is there anything else I am forgetting? Earlier in the year I did the water pump, thermostat, alternator bushings, belts, VC gasket, coolant temp senders (both), cam & crank position sensors and crank damper.


Other thoughts/questions:
I recently picked up a 2006 Jetta TDI, which has been my DD. So the E30 has been getting driven a LOT less, like once every 2 weeks. This makes it a little tougher to diagnose recent symptoms since I have not been driving the E30 much.

I am curious about whether some of my mysterious intermittent poor running is maybe from this thing being partially failed for several months? The car has been acting weird in that about 60 seconds after a cold start, it has trouble idling for maybe 5-10 seconds, and then it goes away after blipping the throttle a couple of times. The ICV is clean, so I am pretty sure it is not that. Could the HG have been leaking a little between #2 & #3 for a while, and it just now fully blew out? It's been doing this for maybe the last 5000-7000 miles, slowly getting worse. I have probably replaced every sensor on the car, and none of it completely fixed the issue.

The last couple of times I drove it, it seemed to be a little hard to start as well. Other than that, it has been running strong all the way up to 7500RPM.

The ICV is making an audible clicking/whirring noise when the car is parked in accessory-II mode. I don't ever recall noticing that before. The tone seems to change if I push on it / move it around. Is this a sign of a dying one?

Here are some shots of the spark plugs that I took today when doing the compression test. These are maybe 15K miles old, and have been through a LOT of fuel/ignition tuning. Do you agree that they mostly look like they have been through some rich running, and hard driving, but nothing much else obvious?

#1


#2


#3


#4

[bmwman91]

I got a little bit of prep done after work today. Mainly, I wanted to completely drain the coolant using the block drain so that there would be an absolute minimum of coolant left in the head. It makes a bit of a mess when you pull it off! I am being extra careful because the repair will be done in my garage, where my cats have access. Coolant is EXTREMELY toxic to cats, who like its taste and smell, and it causes an agonizing death. Anyway, I carefully drained it from the radiator first, and then got the rest out from the block drain using a funnel with a hose under the outlet. There was minimal spillage from there, and I just rolled the car back out into the driveway to hose things down. It'll sit there to dry for a day or two since I have limited time during the week, and it gets dark earlier now with the time change and all (I do not like Daylight Savings Time). I am sure my neighbors are used to seeing me manually pushing the car around in the driveway by now lol.

As a part of getting the funnel under the block drain, I removed the exhaust header. It is super easy to do if you remove the right side engine mount arm (support the engine with a jack). It slides right out the front...as long as you do NOT have A/C installed. If you do have A/C, then you either need to remove the compressor, or the sway bar (and even then I am not sure if it would go out the back).

The coolant did not quite look right. I'd say that combustion gases were definitely making their way into places that they did not belong. This coolant is less than a thousand miles old!






A good amount of debris came out with it, after using the block drain. The dark stuff was almost all magnetic, and I am guessing that this is burned head gasket material.







There was also this bit of paper material in there. I'd guess that it is not from this failure since it does not look burned. Maybe it is just crap from a past gasket that I scraped.




There was a little bit of an indication of trouble (maybe) at cylinder #3's exhaust port. I am guessing that some of the large detonations that occurred in the exhaust when the crank damper was failing had damaged the gasket. It would explain why I thought that the car was making more exhaust noise than usual.




That is it for today. Next steps in the immediate future will be to re-run a compression test after re-charging the battery fully, and using a better compression test kit. It irks me a little than cylinders 1 & 4 were reading low with the loaner compression gauge, and I can't imagine that all four cylinders went out together. Besides, if they were totally shot, I wouldn't think that the engine would run on 2 cylinders at all, let alone enough to get me the last mile home. After the compression test, I will start stripping the rest of the stuff off of the head in preparation for its removal.

[1998ccc]

Lets hope it's the gauge.  Hit up the pawn shops for a good used compression tester.  Most new affordable tools are made in China.

[bmwman91]

It may also be that the oil got washed off of the cylinder walls. I managed to get the car started a couple of times immediately after the initial failure when I was checking stuff in the driveway, but it involved a lot of cranking, so I think that a lot of fuel was passed through the engine without combusting. I will try squirting a little oil into cylinders 1 & 4 to see if that helps to reinstate the seal.

[bmwman91]

I got a look into the cylinders with the borescope this afternoon. I noted multiple HG failures, and I assume that cylinder 3 was the source of the problem. Both cylinders 2 & 4 showed HG ruptures protruding into them, so there must have been a heck of a misfire in #3 at some point. Back when the crank damper went out, I was driving through my neighborhood under light load. The misfires occurred when limping it the last quarter mile home and while troubleshooting in the driveway, so no high RPM operation was occurring at the time. That makes me think that I may have made a mistake (or multiple) when installing the HG in 2013, and that whatever flaws there were in the assembly were made worse by the low-load detonations and then it finally gave up the ghost this last weekend. I'd bet that the inter-cylinder leaks have been there for a while as pin-holes, which would partially explain the bad gas mileage. My increasingly-poor idle and increase in engine/exhaust noise over the last few months could have been the leaks opening up further. Considering none of the external visual and electrical tests I did at any point came up with a cause, this seems plausible as a root cause.

Here are borescope shots of everything. I don't see any immediately obvious indications of trouble beyond the multiple HG failure sites. Despite my best efforts to vacuum all debris out and away from the plug holes, crap still made its way in, so I am not bothering with any compression tests and just going straight to pulling the head. Turning the crank with a wrench also aligns with what I can see. Cylinder 1 has the expected compression/resistance, cylinder 4 has a little resistance and there is none from 2 & 3. Basically, I am sort of surprised that it was running at all.

Now that I look closer, #1 might have also been leaking with #2. Not enough to rupture, but there is a suspicious amount of carbon buildup. Anyway, the period of time in 2013 when I did the HG was not a good point in life on multiple fronts, and I was ready to sell the E30 just to be rid of it. I was stressed, sleep deprived and rushing the repair despite it being my first time doing it. If I really did that poor of a job, then I am glad it failed enough to be obvious so that I can take my time and do it properly this time. I almost don't want to post these pictures because it's embarrassing to believe that I may have done it so poorly!


Cylinder 1


Cylinder 2


Cylinder 3


Cylinder 4

[bmwman91]

So Jim from MM called me earlier. I guess it bugged him that the engine is out on its ass again. Despite repeated mechanical issues with the expensive product I purchased, I have maintained a good working relationship with them. I expressed to Jim that I don't really feel like I ever ended up with the product I paid for, even if the last HG install involved my own errors, and MM would like to try to make things right for good.

The short story is that I am pulling the engine and shipping it out to them. They'll tear it down, and I'll make the call about what to do or not from there. They aren't doing it for free, but it is at a reduced cost that I think is fair. This is somewhat of a "lazy" solution, but I just don't have sufficient time and energy to deal with this correctly myself right now. If MM was not willing to work out a deal then I might feel more motivated since I dislike the idea of throwing money at things, but they seem willing to stand behind their product.

[1998ccc]

Nice of them to stand behind a ~6 year old engine with how many miles?

[bmwman91]

I have put something like 40k miles on it. Yes, I am impressed that they are willing to help me out, granted it is not free, but to offer to do it for a reduced cost is cool.

[1998ccc]

My gut tells me the damper issue started it.  Did you install a M42 or M44 headgasket?

[bmwman91]

It was an M44 HG, the +0.3mm one since the head had been machined multiple times by then.

Yeah, the failed crank damper had something to do with the failure for sure. I got some pretty big detonations when it was coming apart and the ECU lost proper track of timing.

[monty23psk]

Hey there, any updates?

[bmwman91]

Hey, yes! I have been posting mostly on r3v and there is too much to cross post at this point. Post 31 in that thread (link below) is where I guess things diverge from here, although the actual substantial updates start at post 55.

Basically, I have the engine in my garage, all of the parts I need should FINALLY be showing up next week, and I have totally overhauled both the engine wire harness and the whole front chassis wire harness. There is still a little repair work to do on a couple of things (replacing decayed connectors and the crumbly front pad wear sensor cable), and some other minor stuff to address while the engine is out, but I am otherwise ready to get this thing together and running.

https://www.r3vlimited.com/board/forum/e30-technical-forums/engine-drivetrain/m42/9882794-m42-head-gasket-blown-project-thread

[monty23psk]

Good to hear. Just went through it all there. I will keep looking there.

[bmwman91]

Although I am most actively updating over on r3v, I would like to make sure that I share some stuff. For one, I made a full color wiring diagram for the engine harness. See the PDF link for that.

http://www.e30tuner.com/assist/m42wireharness/EngineHarness_M42B18_E30_318iS_OEM.pdf


Also, I am going to be up and running soon. Again, all of the long and boring details are on r3v along with many photos of all the other stuff I have done while waiting for parts, but at this point it is fully reassembled and in the car. I was going to be running a week ago, but all 4 fuel injectors are stuck shut since they sat for 3-4 months after being cleaned. It is apparently a fairly common thing to have injectors stick closed if they sit dry for some amount of time. The 250 cc/min ones I had in there worked, but are a little lower flowing than ideal, and I swapped them for some 300 cc/min ones. Sssquid Tuning cleaned and flow matched my old ones, which sat for too long in my garage, and they were kind enough to let me do an exchange for the higher flowing ones which were also cleaned and flow matched. As soon as I get a chance to burn the updated tune, I should be up and running (maybe tomorrow!).

While waiting multiple months for parts, I completely rebuilt the engine harness, and the entire front chassis wire harness (everything forward of the fuse box). All new Tesa tape, replaced any damaged connectors, and new cable straps. It is so nice to have a proper wire bundle up there now with no sticky goo or crumbling tape. I also totally cleaned up the power wiring for my sound system in the trunk, came up with a much cleaner routing arrangement and 3D printed a nice cable management + fuse holder bracket which mounts onto the gas door lock actuator. Again, pics are on r3v which is linked in my previous post.

Speaking of the engine wire harness, I integrated my MAF conversion and wide band O2 controller into it. This is the wiring diagram which represents the harness that I have in the car now. Eventually I plan to go with a stand alone ECU, probably an AEM Infinity 506, at which point I will have to unwrap it all and make even more modifications.

http://www.e30tuner.com/assist/m42wireharness/EngineHarness_MM2100.pdf

Re-taping it will be super easy next time since it will not be 30 years old and sticky, and the new top-of-the-line Tesa engine harness tape uses an acrylic adhesive (not rubber like the old stuff) so it comes off very cleanly. For those that might want to re-do their engine harness, you will want to buy Tesa 51036 tape in 9, 19 and 25mm widths. I do NOT recommend buying it on Amazon or eBay since those places have tons of fake Tesa tape. You should get it from a reputable distributor. One that I can recommend is Waytek Inc (https://www.waytekwire.com/products?pSearch=51036). Also, you will need paper towels and at least 200mL of 99% isopropyl alcohol to clean off the old adhesive goo. It is a lot of work, but you need to clean the old crap off, and it takes 2-4 passes with towels and alcohol. Oh, and wear some rubber gloves...the adhesive does not come off of your skin very easily.

[monty23psk]

As always, excellent progress.