Head gasket replacement (m30)

[scoobysmak]

I have a 1992 535i with the M30 engine and standard transmission. I live in south Florida and around the end of Dec we had some cooler weather and I was driving home and stopped for gas. I started the car and got about a mile down the road and my temp gauge started for the red zone. It never made it all the way before I shut the car off but was the first thing that happened. I waited about 30 min and then finished my trip home (less than a mile). The next day I checked the coolant level and it was fine. I started the car and the temp gauge never stopped at the "normal" position. I took out the thermostat and replaced it. This seemed to fix my problem so I drove the car for 2 weeks with no problems and then my radiator hose from the water pump to the thermostat housing decided to bust open. Needless to say the car got hot again but not overheated. This time I had to get towed home, funny nobody sells these hoses on a Sat night. Now I go and buy a replacement hose and also the hose from the lower radiator to the thermostat. Well as luck would have it the lower radiator hose was out of stock but was able to replace the one I needed that day. Well then strike 3 happened, the lower radiator hose cracked open, a day before the new hose came in. I replaced this one the next day and everything I thought would be back to normal but as things go two days later I found water in the oil. I took out the spark plugs and it seems number 6 cylinder blew the head gasket. I then purchased a head gasket set and took my Bentley manual off the shelf. I took the head off and got it tested, they found it slightly warped and milled it and the timing chain cover. They also replaced the exhaust valve guides. I put everything back together and have a few problems. One, I have a huge oil leak between the front timing chain cover and the block (I lost 1/4 quart of oil in 14 miles, it seems that it dumps most of it when I shut off the motor, it even manages to squirt on the lower radiator hose). This should be obvious to fix but figured I would ask to see if there were any tricks that I should have done the first time. Second, the car idles rough and I am missing power above 2500 rpm. This second problem worries me more, I admit that I need a professional to adjust my valves, I tried for 2 hours to get them right but they still let me know that they need a better tuning. I asked and someone told me that I may have placed the cam in the wrong position causing both problems but I put the cam lined up with the head like the instructions said (along with having the lower end at TDC for cylinder number 1). The check engine light comes on erratically also, I got the code checked and it looks as if water and my O2 sensor did not get along with each other. Not sure if this could cause a problem or not but the check engine light does not say on. The only other hint of a problem is when looking for the oil leak I had the car in my garage and when I started it. It runs really rich, I could smell gas in the air like I spilled it all over the floor. I know this is part of the 02 sensor and just being cold but just giving as much information as possible to get my car back on the road.

[duckloads]

I might be wrong but,

Could your oil leak be coming from the timing chain tensioner bolt? There is oil pressure on the tensioner. That Might cause such a rapid oil loss. I can't imagine why it would dump oil at sutdown.

The last time I adjusted my valves, I turned the engine until each cam lobe's heal was on the follower. It required a bit more turning of the engine, but setting each cyl at TDC didn't put each heal 180 deg from the follower. It might not matter, but it made me feal better about it anyway.

What code did you actually get?

Good luck. Someone who really knows will come along soon.

[Kalevera]

You probably already know this...but perhaps the sequence of bolts used when reinstalling the timing chain cover was mixed up? All of those are different sized bolts and have to be installed in the exact same spot, IIRC.

The first thing to do regarding the oil leak is to determine exactly where it's coming from on the sucka .

I've never had the occasion to change my O2 sensor, but I recall reading that one of the things that it definitely doesn't like is sniffing a lot of burnt coolant. Perhaps just change it? The other thing I was thinking re: check engine light is that something simple might have a loose connection (or not be connected at all) a la ICV or MAF. Of course, losing oil pressure can't be helping anything very much.

best, whit

[George M]

Would say most of your issues are in how you put it back together...but you likely know that. It really is all in the details. If your valves are loud, could very well be a slack timing chain as you very well may not have pumped the tensioner up properly...very common. Also many do get their cam set wrong when they put it back together...you have to get all the slack out of the driver side of the chain opposite the tensioner or very easy to be a tooth off. The tensioner piston plug has to be loose as you pump the tensioner or you can't purge all the air in the system. The little oil reservoir has to be full as well. After pulling the valve cover...double check for good oil distribution...make sure you put the oil distribution bar back on properly...> should point forward for proper hole alignment under the bar to each rocker. As to the oil leak...if you didn't remove your lower timing chain cover, then its likely how you attached the upper cover. Did you use a high temp gasket dressing? A common leak path from the upper timing chain cover is the long carriage bolt for the CPS...needs to be siliconed. Completely degrease the cover and double check the leak path. Personally if you are losing copious amounts of oil out front, I would remove the cover and start over. While apart, double check the cam and timing chain tension.
Don't get discouraged...your answers are in front of you and you will figure it out...the big six is wonderfully simple and robust.
George

[scoobysmak]

Thanks I am going to look at it again, pumping up the tensioner could be an issue. I got the head service and they put it back together but I did not look over there work (it is a very trusted shop in the area, not an excuse but I do not believe they would have messed up). The lower timing chain cover never came off so it has to be the upper cover. I am sure the bolts are correct, I put them on a cardboard cutout and they went in the exact same hole they came from. Something else I was told is that this motor runs with an internal vacuum on it. They told me to remove the dipstick at idle and it should start to run rough if you have a oil leak due to the nature this engine runs. I admit it doesn't idle that well to begin with but it gets worse if you remove the dipstick so it seems as if I do have a vacuum just dumps oil out when I turn it off. I appreciate everyone’s help, back to the garage.

[George M]

Take it back if they put the head on. They likely won't be able to fix it if they didn't do it right the first time. You would be better served to take a stab based upon what I wrote above. If you have any questions about precisely setting up the cam...exactly sure that is...be sure to post....the cam gets set to cylinder bore centerline...not to the ground. So the 7 o'clock cam sprocket reference hole is 7 o'clock to the cylinder bore centerline...not to the ground. The sprocket bolt holts are perpendicular to the cylinder block deck...not the ground. The engine is laid over 30 degrees. The chain has to be taut on the driver side when you place the sprocket back in place with the chain on so the tensioner can take all the slack out of the chain on the passenger side when you pump it up properly. Set all your valves to .012-.013 cold. Go around twice. A single valve out of adjustment will cause the big six to not run right.
Good Luck,
George

[scoobysmak]

Well I took the distributor off and was planning on taking the upper timing chain cover off but found something interesting. For some unknown reason (probablyl my stupidity) the bolt holding the rotor assymbaly was not tight (of course this screws into the cam). I severly injured the cap and rotor and there was oil all inside so I might have found the oil leak but want to make sure there are no other leaks. I replaced the gasket where the cam comes through on the timing chain cover so that shouldn't leak after I put everything back together "properly". The main question I have is priming the timing chain tensioner. I see in the manual they say to pour oil down inside the timing chain cover but is there a better way? I haven't checked to see if the cam is lined up but I am sure that I based the position from the pictures in the manual that it is correct (unless it moved because of the tensioner not being set right. Thanks for all the help

[George M]

at this point, IMHO, its a no brainer. I would pull the upper cover off and make sure the cam is timed correctly. For the cam rotor countersunk allen cap screw, you want to apply loctite 242 and make sure you don't over torque it. Those that have sometimes hold on to a nice broken off piece of camshaft. There is a reservoir/pocket on the most passenger side rear quadrant as you peer into the opening made my the upper timing chain cover at the front of the engine as you remove the valve cover. This reservoir automatically fills with oil when the engine is running by run off from the valve train pumped up from the bottom end through the oil distribution bar. You need to manually keep that reservoir filled when the engine is off and you are pumping the tensioner guide. Oil (and air) should wick past the threads on the tensioner plug which should be loose as you pump up the tensioner. Use a long neck trans funnel if you have one to keep the reservoir full of oil so you don't introduce any air. Any oil spill over simply falls into your pan sump...no big deal.
HTH,
George

[scoobysmak]

Well I finally got time to work on my car again. I took the upper timing chain cover off and took a few pics to see what everyone else thought too. I do belive it jumped one tooth but figure I would ask. The pics were taken with the crank at TDC and I do not have the tensioner back in. Any comments would be appreciated, thanks for your help. *Edited*- I had to add my pics one at a time.

[genphreak]

Be absoultely clear, the engine runs on a slant- not straight up and down.

From what I can tell the Bentley manual relates all things in the valve-train to the horizontal of the block itself- this is at around 30 odd degrees to everything else on the car, so when they say note the gear's bolt positions at N-E-S-W, its point of reference is the cylinder head/block surface, not the car/road/you.

One thing u must do... is make sure those 2 pesky dowels are where they should be in your upper timing cover, if not, the cover may not be on square and true to the engine... perhaps causing oil loss may then occur from where the gaskets butt, or from the seal around the rotor cap as it won't be centred right. The Bentley manual does not mention these dowels at all, although it does tell you where to put the different length bolts in the upper TC cover .

It's very easy to loose em when u drop the cover and head into the shop for machining!

PS- I used Hylomar to seal my timing covers, worked a treat on the new gaskets. No leaks, zip.

oh, before the valve cover goes back on, make that timing chain piston is primed... but u know that I am sure.

Best of luck, am sure you'll be ok. The issues come down to torquing the head right. If you have a leak, just replace the head gasket and use NEW head bolts. I doubt you would have warped it, but watching the air bleed very carefully- check a few times to get it all out and be prepared to change hoses and clean the connections with a wire brush so they will seal well again. A leaks that introduces air into the head overnight may cause overheating the next morning. Should make for religious bleed (ie engine off, filling with coolant) in the morning a few days after you see no bubbles whatsoever come through the bleeder and you are happy its is all bedded in.

Torque them as per the manual. Mine worked out fine...

Oh, and your O2 sensor is probaly dead from the coolant vapor in your exhaust. If coolant is in the oil the engine must be shut down and the oil changed, its just that leaks make this damn near impossible.

If its any consolation, my head gasket needed to go at 17, and it went naturally without abuse... they are long engines, can only thinkg that heating up and cooling down all the time creates a lot of localised longitudinal stresses in the gasket... let us all know how u end up.

GP