M30B34 head gasket replacement - inexpensively?

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Mab1957
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Joined: May 14, 2010 1:33 PM
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M30B34 head gasket replacement - inexpensively?

Post by Mab1957 »

I've got a leaky head gasket in the 85 535i project car. (another reason it was only $300 :roll: ) I did see oil in the coolant I drained when replacing the cut radiator hose on this motor. It runs well, a bit of white smoke that dissipates at idle, a plume under load. It has not overheated while in my possession.

Based on this:
slimdevil27 wrote:There are several ways that a head gasket will fail and each will produce different symptoms.

First are the compression leak failures. In nearly all of these failures drivability problems such as misfiring will occur. If the head gasket fails between two cylinders you will have low compression on both cylinders, misfiring, and usually backfiring into the intake tract, which can blow off vacuum hoses and intake boots. A compression test will verify this type of failure with low/no compression on two adjacent cylinders.

The other type of compression leak is into a coolant passage or oil passage.
With a leak into a coolant passage you may or may not have coolant leaking back into the cylinder. The failure may act as a one way valve and only leak at pressures higher than what the cooling system runs at. They may also only become evident at high rpm and under load. This is the early stage before complete failure that will allow coolant back into the cylinder. This may cause misfiring, oil contamination (milkshake appearance), white smoke from the exhaust and a no start condition. The no start will happen when there is coolant in the combustion chamber and the engine tries to compress the fluid. Fluid cannot be compressed, you can only apply pressure to it. This is referred to as "hydro-lock". If this happens while driving, severe engine damage can occur. Broken piston/rings, bent rods, thrown rods, etc. If it happens when trying to start the engine, don't worry, none of this is likely to occur. With hydro-lock you will distinctly hear the solenoid click and the starter engage, the engine may turn over once before clunking to a stop. Subsequent attempts will produce very little turning of the engine, but again you will feel the starter engaging and trying to turn the engine. Stop and pull the plugs, the waterfall of coolant(or gas from a leaking injector/carb) will be readily apparent.

A compression leak to oil passage leak, on most engines, is unlikely. The reason is that most passages are on the periphery of the block with coolant passages between them and the cylinder. Some older straight 6 cylinders have pushrod passages that run close to the cylinders and these are the type that may have this type of leak.

The last type of head gasket failure is from a coolant passage to an oil passage. Since there is no loss of compression in any of the cylinders, drivability is not affected and usually the first symptom is overheating due to a low coolant level. The oil will have the typical milkshake appearance. On some types of engines this is not conclusive for a head gasket failure. In particular the Toyota 22R engines have a tendency for the timing chain to wear through the front timing cover exposing the coolant passage that feeds the water pump. This only occurs if the timing chain guide (plastic like ours) disintegrates.
An oil galley to coolant passage would pump oil into the cooling system, it's possible but I've never seen it.

For diagnostics- Determine which conditions apply. Check the oil first, that's the easiest.

Milkshake appearance of oil- Coolant to oil or coolant to cylinder. The later accompanied by white smoke from exhaust and misfiring of that cylinder.

Coolant loss from overflow-Combustion to coolant-The main symptoms to look for on this type of failure is immediate pressure in the cooling system on start up/revving. On a cold engine, with the cooling system full start the engine. Squeeze the upper radiator hose and rev the engine. If the hose starts and continues to build pressure then you most likely have a compression leak into the cooling system. This is the very beginning stage of head gasket failure. The single best way to verify this type of failure is with a block tester as mentioned. Most of these test kits are $50 or less.

http://www.amazon.com/Lisle-75500-Combu ... 789&sr=8-2

The tube is placed on the radiator cap opening and the test solution is added. With the vehicle running any compression gasses will bubble up through the test solution. If HC (hydrocarbons) are present the solution will change color, typically from blue to yellow.
If you have pressure remaining in the cooling system after it's completely cooled down, say overnight, or slimy black gunk in the overflow even without noticeable overheating you should block test it with a kit.
The more dramatic way that this presents itself is with a blown hose or blown radiator. The sudden pressure spike of combustion pressure into the cooling system finds the weakest link, the path of least resistance and promptly blows it up to let you know. It's advisable to do a block test anytime you have a ruptured hose that by appearance doesn't look bad or feel soft and squishy and definitely anytime the plastic on a radiator shatters.

Coolant loss, misfiring, white smoke- Coolant to cylinder. In the beginning stages you may notice a rough run on cold start and white smoke that dissipates. This is caused by seepage into the cylinder as the cooling system depressurizes while cooling down. As it gets worse the white smoke will be continuous. The oil may gradually become milky as the coolant leaks down past the piston rings. Pull the spark plugs and look for one that's clean. The steaming coolant does a really nice job of cleaning the combustion chamber and piston as well. That was actually how they cleaned the engine way back when. Run it at high rpm hot and dribble or spray water into the carb. Effective, but not recommended. Anytime you are losing coolant and can't immediately identify the source, and after repairs, a cooling system pressure test should be done. You may be able to rent one from the local auto parts store. On our engines you can disconnect the cooling reservoir return hose, clamp a cap to the reservoir and attach the hose to a bicycle pump, or attach it to the reservoir and securely plug the hose. Any pressure over what the radiator cap is rated for will be vented and the rest of the system will be pressurized. This is helpful for slow seepage that steams off leaving no wetness and also in and around the front of the engine. Weaving an inspection mirror in past a spinning fan and belts is not a good idea. If no external leaks are found then pull the plugs and either look in the cylinder, I use a bore scope, or roll the engine over by hand watching for spillage from the spark plug hole. 1/4 cotton rope makes an excellent dipstick to thread into each plug hole, wet a green is not good. If at first you don't succeed then let it sit pressurized for 10-20 minutes and retest.

The cylinder to cylinder blown head gasket typically presents as a rough run. Pulling the plugs will usually show which two are leaking, however a compression test will confirm this. It's a good habit, especially when doing a tuneup on a rough running engine, to do a compression test every time. With a remote starter switch this can be done in 10 minutes or less and besides the plugs are already out.

The only cracked heads that I've seen are on engines that were run after overheating and the owners just added coolant and kept on running it or they were run low quite some time. Some engines are more prone than others but it's usually neglect that precipitates cracking.
I shouldn't take a chance driving it the few hundred miles back to NC for that next phase of my project. Searchy reveals a few head gasket replacement threads:
M30B35 head gasket DIY for dummies
Head Gasket M30B34

I've tried a few searches here for a M30B34 head gasket DIY thread. While I'm looking, what tips do you MyE28rs have to share about M30B34 head gasket replacement?

This motor will only be in this car temporarily. I'm going with a different motor eventually. It has high but undocumented mileage and I only want it to be dependable during the build so I can move the car to various locations within Virginia and the Carolinas. I don't want to spend much more money on the motor. I got another head with it, but haven't identified what it is (PO was planning to build and swap it into this car - he did not tell me the existing head was positively bad)

What are your thoughts on my lifting the head, replacing the gasket and then just go merrily on my way? - i.e. no machine shop cost. :dunno:
ahab
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Post by ahab »

I can't really say much without knowing more about the nature of the problem, however oil in the coolant is bad and far worse than the other way around.
slammin_e28
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Post by slammin_e28 »

I'd be afraid of the head being warped from getting hot, main concern. If it is, a new HG really wouldn't do much good.

But, if it's not, you get out with the cost of a HG. Can even reuse the bolts on M30s. Lift it (exhaust and intake manis attached) with an engine hoist, hit the block with a scotch bright pad, clean the head surface as best you can, slip the new gasket on there, and slam it back together.

You'd be out the cost of a HG, cleaning supplies, some oil, some coolant, and about 8 hours (or less) if it didn't work.
turbodan
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Post by turbodan »

The M30 is very likely to mix coolant into the oil when the head gasket fails. Oil in the coolant would be unusual.

If I were you I'd closely monitor coolant and oil levels to see what you're burning. Sounds like it could be oil, in which case the HG would be a waste of time. If you're burning coolant I would also expect coolant in the oil. The combustion chamber pressure is much higher than cooling system pressure as well, so you would almost certainly see excessive cooling system pressure resulting in coolant purging.
Mike W.
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Post by Mike W. »

You might be able to get away with just a gasket, but if it was overheated that badly the head probably warped, causing the gasket to blow not the other way around. So a new gasket might help, but it's the symptom not the problem. Getting the head surfaced is no big deal, except you have to break it down first which is a PITA. And if it's got a significant warp the rocker shafts aren't exactly going to slide right out easily. Then if you're that far, you might as well do valve guide seals, then a valve job, then... It's how a $100 head set turns into $500-1K.

If it was me I'd either look for a good used head, and sometimes people sell them cheap but it's hard to find one that's flat and I won't put one on if it's not.
wkohler
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Post by wkohler »

I've seen a few cars mix oil into the coolant. Rare, of course. bought a new coolant bottle off of one in the yard. ick. Then some idiot pulled the motor after I told him it was trashed. :lol:
Mab1957
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Post by Mab1957 »

This is the other head I got with the car. Has M30 in the casting, is it B34?
ImageImageImage
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Looks like it sat outside for a season, has pine needles and mud dauber nest in it. :(
slammin_e28
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Post by slammin_e28 »

B34, second pic with the "85" in the circle.

I'd clean it up, check it with a straight edge and slap it on, as long as the cam wasn't rusty from sitting out. Of course at that point you're better off getting the entire HG kit with all the gaskets.

I had spare everything, intake, exhaust manis, etc, so I bolted it all to the head without removing jack shit from the old head. Slapped her back together with Mike W's torque specs, found searching here, and she ran like a top.

I did it for under $200, of course I got the parts thru work at 10% over cost.
Mab1957
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Post by Mab1957 »

slammin_e28 wrote:B34, second pic with the "85" in the circle.

I'd clean it up, check it with a straight edge and slap it on, as long as the cam wasn't rusty from sitting out. Of course at that point you're better off getting the entire HG kit with all the gaskets.

I had spare everything, intake, exhaust manis, etc, so I bolted it all to the head without removing jack shit from the old head. Slapped her back together with Mike W's torque specs, found searching here, and she ran like a top.

I did it for under $200, of course I got the parts thru work at 10% over cost.
Thanks, Jeff. Based on this:
ahab wrote:The last few I've bought were the Victor Reinz set from either Pelican or Autohausaz. An old Steve Haygood tip, you can buy the B35 set along with a set of B34 intake manifold gaskets. These are the only difference between the two sets and is about $10 cheaper that way. If you end up doing that I'll throw you a few bucks for the B35 intake gaskets. Recently Blunttech has made a push to be a "local" supplier and many here have had good experiences using them.

The only other tips I would recommend is to get a bottle of Permatex Aviation Form-A-Gasket No. 3 and use this along the upper timing chain cover and the hoop that separates it from the lower. Set your motor on TDC before you start, and wire tie the chain to the cam gear in a couple of places as soon as you take it off the cam. Everything else you'll need to know regarding the job is readily available here.
Does Rich in Tupelo's VR B35 kit fit the bill (oops - may have just missed that), or do you recommend a B34 HG kit? The cam is a bit rusty, but I'll clean it up.
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slammin_e28
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Post by slammin_e28 »

Mab1957 wrote: Thanks, Jeff. Based on this:
ahab wrote:The last few I've bought were the Victor Reinz set from either Pelican or Autohausaz. An old Steve Haygood tip, you can buy the B35 set along with a set of B34 intake manifold gaskets. These are the only difference between the two sets and is about $10 cheaper that way. If you end up doing that I'll throw you a few bucks for the B35 intake gaskets. Recently Blunttech has made a push to be a "local" supplier and many here have had good experiences using them.
Well shit. I didn't know that. Just looked them up and could have saved myself another like $20, lol.
ahab
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Post by ahab »

While the date stamp is a slam dunk, the other way to quickly tell which version of the head you've got is the shape of the intake ports. The B35 ports are much more kidney shape. Hence the different gaskets. If you do get a B35 kit, my offer still stands on the gaskets.

B35 version here

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