O great BMW Oracles of Knowledge - 95 525 Head Gasket ;(

[Scott C]

Well,

Looks like Santa dumped the turds on me this Xmas, the headgasket in my 95 525i appears to be leaking both oil and antifreeze at the far back of the engine above the bell housing. The antifreeze is leaking at about 1 quart every 3-4 weeks and oil is less than a quart at 3K miles (but will need to watch).

I drive this thing to and from work (5 miles each way) and don't abuse it - straight and level simple drive. The crystal ball question is, can I with moderate risk continue to drive this (watching the temp gauge) through the winter until weather is warmer or am I jeopardizing head warpage by doing so? I am not familiar with the failure modes of this puppy, but know it is gonna cost a fortune if I warp the head.

Anyway, that is the question - looking for opinions as to how stupid this would be based upon known experience with head gasket failures on the M50TU engine!

Thanks much in advance,
Scott

[colo525i]

I'd check for a leaky heater hose first before being certain it was the headgasket. Has the car ever been overheated?
The oil could be the valve cover gasket, they like to get rock hard and let oil go everywhere. Also check the coolant for oily spots. You can also check the spark plugs to see if they are clean of deposits. The M50 is prone to headgasket failure if it is overheated, but they tend to go quite catastrophically.
Don't see any reason to stop driving if it isn't overheating as that is what causes the warped head.

[Scott C]

I'd check for a leaky heater hose first before being certain it was the headgasket. Has the car ever been overheated?
The oil could be the valve cover gasket, they like to get rock hard and let oil go everywhere. Also check the coolant for oily spots. You can also check the spark plugs to see if they are clean of deposits. The M50 is prone to headgasket failure if it is overheated, but they tend to go quite catastrophically.
Don't see any reason to stop driving if it isn't overheating as that is what causes the warped head.


Thanks,
The heater hose was replaced 1 year ago (the hard to replace one under the intake man) and it seems to be sealed tight at the fittings). The valve cover gasket was changed this summer but I will double check to make sure I did not cock it up...

Edit... I verified that the valve cover gasket is in well and that the hoses are tight and not leaking. I just love working in garage that is at 40 degrees :)

[scott 4991]

Well Scott C, you got my original name - many years ago I was Scott C - but no more.. anyway, I had a similar problem on my 535i. This was a 3'rd car, so I did not need it to drive everyway, and my son and I took the engine apart, with the help of Bentley, and replaced the timing chain, had the head trued, water pump, all associated parts - and it's been fine ever since. I now have 172K miles and it runs great. Don't know how long you plan to keep the car, but if for a while, why not do this? My head truing and valve seating ran $440 at a high performance shop - not through a dealer. I considered this a good price. I'd sure we spend $800 when finished, but still running strong at 172K miles is great.

To address your question, I think you can drive it as it, as long as you watch for overheating and watch the oil.

Good Luck.

The old Scott C

[Scott C]

Thanks,
I intend to fix it long term (and keep the car 4 or so more years), it is just that with the snow coming here in the great white north and the fact that this is the car I have to drive (and with Blizzaks - big grin) and really don't want to tear it down while it is cold. I am researching whom can do the head locally (grind, seats, etc) and am reading about all the wonderful tools needed to potentially do this job (with the vanos).


Well Scott C, you got my original name - many years ago I was Scott C - but no more.. anyway, I had a similar problem on my 535i. This was a 3'rd car, so I did not need it to drive everyway, and my son and I took the engine apart, with the help of Bentley, and replaced the timing chain, had the head trued, water pump, all associated parts - and it's been fine ever since. I now have 172K miles and it runs great. Don't know how long you plan to keep the car, but if for a while, why not do this? My head truing and valve seating ran $440 at a high performance shop - not through a dealer. I considered this a good price. I'd sure we spend $800 when finished, but still running strong at 172K miles is great.

To address your question, I think you can drive it as it, as long as you watch for overheating and watch the oil.

Good Luck.

The old Scott C

[winfred]

as long as you don't overheat it or run out of oil it will probably be ok, be advised theres always the possibility it could blow a chunk of gasket out and the drip turns into a gush so beware

[Scott C]

as long as you don't overheat it or run out of oil it will probably be ok, be advised theres always the possibility it could blow a chunk of gasket out and the drip turns into a gush so beware


That is exactly the type of failure that I was worried about - a catastrophic failure that screws the engine....

Thanks much Winfred!

[Scott C]

Not to beat a dead horse....

Based upon years of experience, car with 115K miles and assuming the head does not need reground, should I just go ahead and get a valve job (and seals replaced) while it is off? I should note that there is currently no smoke from the car (either under heavy load or coasting) but my usual philosophy is to just get 'er done while in there. I am somewhat reluctant to take the head to a shop and have them work on it as my experience to date is not good with local shops (rural NY).

It seems a no brainer if I have to plane the head to get the valves done....

Thanks much.

[winfred]

it should be fine, the non vanos m50s had problems with valve guides but the vanos cars seem to be fine, and 115k ain't much mileage the stem seals are probably still flexible, at most (unless given cause) id lap the valves and knock on new valve stem seals, otherwise if it's clean and straight throw it back on with new head bolts

[Scott C]

it should be fine, the non vanos m50s had problems with valve guides but the vanos cars seem to be fine, and 115k ain't much mileage the stem seals are probably still flexible, at most (unless given cause) id lap the valves and knock on new valve stem seals, otherwise if it's clean and straight throw it back on with new head bolts

Thank you very much kind sir!
Scott

[Scott C]

So I am trying to find the tools to do this job using the Bentley and have come up with the following needed items:

112300 Crankshaft lock
113240 Camshaft lock

113290 Timing tensioner
Torx E10
Torx E8
112250 Torx E12 Special wrench
112110 Tightening protractor
114230 Rigid chain tension

I assume that these really are needed or is there a subset that works adequately? (I am very surprised at the tightening sequence for the head bolts). I have read that Winfred has written a procedure for doing this with minimum tools? (But have not found it)

Thanks much!
Scott

[winfred]

if you are handy and quick with a wrench it can be done without the lock down tools but you can **** up, i've typed how to do it a few times over the years so search around, it's a bit of a pain in the ass to type it all up and if i absolutely don't gotta do it i won't.

tools
the crank lock is not necessary just keep a eye on the tdc mark
the cam locks can be gotten around with careful watch and use of a straight edge
the regular tensioner does just fine
the e8 does 3 or 4 little bolts up be the cam gears
the e10 does the bolts on the exhaust cam gear (intake cam on non vanos too)
e12 does the head bolts
protractor, bah! seriously you can't pull a 90* degree AKA 1/4 turn without looking at a pointer?!
the head bolts are not a big deal, a drop or two of oil on the threads, the holes must be free of liquid or you could crack the block, 1st stage 22 foot pounds 2nd 90* 3rd 90* tighten in a X pattern starting in the center

11 7 5 1 3 9 14
13 8 4 2 6 10 12 or

13 9 5 1 3 7 11
14 10 6 2 4 8 12 would work fine (this is the pattern i usually use as it's easy to remember)


So I am trying to find the tools to do this job using the Bentley and have come up with the following needed items:

112300 Crankshaft lock
113240 Camshaft lock

113290 Timing tensioner
Torx E10
Torx E8
112250 Torx E12 Special wrench
112110 Tightening protractor
114230 Rigid chain tension

I assume that these really are needed or is there a subset that works adequately? (I am very surprised at the tightening sequence for the head bolts). I have read that Winfred has written a procedure for doing this with minimum tools? (But have not found it)

Thanks much!
Scott

[Scott C]

if you are handy and quick with a wrench it can be done without the lock down tools but you can **** up, i've typed how to do it a few times over the years so search around, it's a bit of a pain in the ass to type it all up and if i absolutely don't gotta do it i won't.

tools
the crank lock is not necessary just keep a eye on the tdc mark
the cam locks can be gotten around with careful watch and use of a straight edge
the regular tensioner does just fine
the e8 does 3 or 4 little bolts up be the cam gears
the e10 does the bolts on the exhaust cam gear (intake cam on non vanos too)
e12 does the head bolts
protractor, bah! seriously you can't pull a 90* degree AKA 1/4 turn without looking at a pointer?!
the head bolts are not a big deal, a drop or two of oil on the threads, the holes must be free of liquid or you could crack the block, 1st stage 22 foot pounds 2nd 90* 3rd 90* tighten in a X pattern starting in the center

11 7 5 1 3 9 14
13 8 4 2 6 10 12 or

13 9 5 1 3 7 11
14 10 6 2 4 8 12 would work fine (this is the pattern i usually use as it's easy to remember)

Thanks much - will keep searching!
Scott

[Scott C]

Winfred, Jeff and other E34 Masters,

Got the tools for doing the valve job on the M50TU (call me a chicken, now that I have them, I see that I could have done without...) and finally pulled the head off. I had been seeing oil and anti freeze coming out the last cylinder near the tranny for some time. I finally had a catastrophic failure in that coolant system overpressurized and came out the radiator cap, which was a little loose or the radiator likely would have blown. The coolant was bubbling real well but the temp gauge never went to red until I stopped the engine and it spiked up. Yes, I win the wanker award for this...

Anyway got the head off today and first thing noticed that the bolts were only in with 50ft lbs of torque (had to measure even though these are not torqued the normal way) which seemed really loose to me. I was able to remove the head and not break the timing chain guide due to the postings from the site reminding one to be careful.

Anyway the question is the following: Up until the coolant system over pressurized, I was just planning on verifying the straightness of the head and then putting it back. Now I am worried that I may have a crack in the exhaust area - how else would coolant over pressurize - possibly the gasket allowed combustion gasses into the coolant? (EDIT - I attached a picture showing the area the coolant and oil leaked..)

I think I should take this to a head shop for pressure testing - but wanted an opinion from someone whom has done this before.

This was my first double overhead cam (and last one I do)....

Thanks much in advance, Scott

[winfred]

the common m50 crack points are between the valves and from one of the exhaust valves to the water jacket opening or a head bolt hole, i've not really had much luck with getting them pressure checked (atleast around here) generally the crack is not hard to see and usually easier to spot right off the engine without cleaning if it's between the valves

[Scott C]

the common m50 crack points are between the valves and from one of the exhaust valves to the water jacket opening or a head bolt hole, i've not really had much luck with getting them pressure checked (atleast around here) generally the crack is not hard to see and usually easier to spot right off the engine without cleaning if it's between the valves

Will check when I am more noticeably alert tomorrow after work... Thanks again!
Scott

[Scott C]

Will check when I am more noticeably alert tomorrow after work... Thanks again!
Scott

Well the head is not cracked and it is not warped!!!!!!! Found a buddy with a proper machinist's ground straightedge.... Now 2 days of fun getting this back together. Thanks much Winfred!

[Scott C]

After doing this head gasket job, I have several suggestions to other people interested in doing this your self:

#1 - I CLEARLY understand why the dealer wanted $1200 to do this job (that was assuming no head or other damage) and all I can say is the mechanic EARNS his money on this job.

#2 - There are lots of areas to go wrong on this according to the Bentley manual - this is not for the faint of heart. This was my first (and last) double overhead cam job. I have the Vanos and bought the cam alignment tool and after using it can see how others would successfully use a metal straight edge. I also bought the flywheel lock but could not get it in right and "eyeballed" the position using the marks in the front of the engine near the crank sensor. I relied heavily on the fact that the parts had some discoloration (an aid to re installation) as well as clearly marked the chain and pulley with a marker prior to removal to aid in resinstallation.

#3 - The simple act of removing and installing all components and getting them back together was an interesting challenge as I tore apart on one weekend and reinstalled the following weekend (waiting for parts in between) and after having a chance to inspect the parts I removed for warpage, etc. I would recommend not waiting this long.

#4 - The pure pucker factor when starting the engine for the first time (even though I turned it multiple times by hand to validate timing). Nothing else like it knowing that you are looking at a ton of money if somewhere along the way you screwed up.

#5 - I got burned by coolant air bubbles and thought the darn head was bad even after inspection and reinstallation. I pulled the water pump thinking (and at the time hoping) it was bad, saw it was good and reinstalled, loaded coolant through the upper hose into the block and waited for an hour. I also drilled a hole through the thermostat. This time I quickly got heat and as a result knew all would be well. The first time was not so great as the car overheated at idle (shut off quickly, but temp needle was jumping up fast) and this was obviously due to a big bubble in the head/block.

#6 - I don't think I could bring myself to do this again - this was a lot of work and for a daily driver, I should have taken it to a professional I trust (that was the problem - not sure whom to go to...).

#7 - This site is INVALUABLE in even thinking about doing this - thanks to the many folks whom have contributed good info. Especially Winfred for his quick and accurate responses

Scott

[clindahl]

Congradulations on the successfully head gasket change. I have not done one on the BMW M50 engine, but on another manufacurer's V6 DOHC, and there is quite a bit to do. Granted that engine is non interference w/ a timing belt so there is not SO much worry about when turning the key, but I still know the feeling of finding out if all your hard work was right, or all that money out the exhaust. Congradulations on a job well done!

[Dave M]

You'll do it again :D If you're good enough to do the M50, all your 'friends' will be pulling their smoking, leaking heaps into your garage for you to fix. Thats the boat I'm in now. Just did a 95 golf headgasket on the weekend.

Dave M

[winfred]

i have squashed all but a couple leaches, the remaining ones either pay fairly well or amuse me, i value my one day off and have no problem with saying no


You'll do it again :D If you're good enough to do the M50, all your 'friends' will be pulling their smoking, leaking heaps into your garage for you to fix. Thats the boat I'm in now. Just did a 95 golf headgasket on the weekend.

Dave M

[Blitzkrieg Bob]

now that you've done it, buddies will show up with beer and parts looking for help.

[winfred]

yea but i know where to buy beer and not piss away my weekend, i bet scott can find the beer store too
http://www.thebeerstore.ca/images/posters/beerwallpaper_5_1024x768.jpg


now that you've done it, buddies will show up with beer and parts looking for help.

[Scott C]

yea but i know where to buy beer and not piss away my weekend, i bet scott can find the beer store too
http://www.thebeerstore.ca/images/posters/beerwallpaper_5_1024x768.jpg

I have to admit, I would have been tempted to drink very heavily if this did not fix the problem - that was a LOT of work and even though I found a place that would swap a rebuilt head (ground valves, seals, pressure tested, milled) for $950 + $50 shippping, I would have been in tears (YES TEARS) just thinking about having to do the swap again.

To top it off, the refrigerator died just prior to this, and that was sadly a big expense (it was a 30 yr old subzero and of course not much else fits in 24" depth location - it did encourage me to get my EPA certification so I could buy R12). My son's car (neon, my backup) was torn apart for rusted brake and fuel lines (yes he started it during break 2 months ago, you get this picture) and that was my backup. So I have been driving a 1982 Mazda RX-7 (project) that looks like hell (but is mechanically very sound and has NO rust, just awaiting paint) during this fiasco.

Scott

[Scott C]

now that you've done it, buddies will show up with beer and parts looking for help.

Buddies won't cut it, better be the budwieser girls or I won't be touching that car!

[winfred]

sounds like my first car a 83 rx7, looked like ass paid $300 for it did a brake job and a tune up or two over 30-40k miles and sold it for $300 when something died in the starter circuit and i didn't feel like screwing with it. probably the most fun you could have with 100hp


So I have been driving a 1982 Mazda RX-7 (project) that looks like hell (but is mechanically very sound and has NO rust, just awaiting paint) during this fiasco.

Scott

[Scott C]

sounds like my first car a 83 rx7, looked like ass paid $300 for it did a brake job and a tune up or two over 30-40k miles and sold it for $300 when something died in the starter circuit and i didn't feel like screwing with it. probably the most fun you could have with 100hp


It is a ball to drive - no antilock brakes, no traction control - if I want to spin the wheels (in first gear only of course with 100HP), I can.

FYI - I used to have a lifter noise after the 525 was warmed up - now strangely after replacing the head gasket - the engine purrs like a kitten with no clatter - not sure why but I am not complaining. (The only diff I used cheap 10W40 oil vs M1)