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Discussion Starter · #1 ·
Hello all,

This is my first post although I have been lurking for a while sponging up tons of useful information, Thank You.

I have a laundry list of questions but this seems to be the most urgent so any help would be greatly appreciated.

I recently picked up a 91 750il for $400.00 as a project (Boy I had noooo idea! But im in it now). The guy I bought from said it had a blown head gasket. But after a test drive and some quick checks of the fluids that didnt seem to be the case. There was a little smoke at start up, but after warming up a bit it seemed to rectify. Yet it did have a slight miss when idling. after fuel injector cleaner and a higher octane fill up the miss has dramatically reduced yet after changing the oil (which was waaaaaay overdue) it started to smoke (white) quit a bit. Im not sure if someone had put an additive to prevent the smoke or what but there is definately a problem.

I found a few posts regarding the OSV/PVC causing smoke but the symtoms usually mention suction in the dip stick. Yet there is no suction.


Question:
Could the OSV cause smoke without the suction symptom? Or could it still have a blown headgasket without sharing fluids ie:eek:il in coolant???

Thanks
 

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It does sound like the OSV, the classic symptom is it smokes a little on start up and the disappears as you've said, so I'm pretty sure its the OSV and it doesn't always make the sucking noise at the dipstick, that only occurs if its gone really bad, If the head gasket had gone it would smoke all the time with oil or fluid lost.
 

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Discussion Starter · #3 ·
Thank you for a quick response one more added quirk. As mentioned after an oil change the smoking increased a lot but does seem to be intermitant, drive for a bit it will stop. Let it idle and the smoking starts again. Do you know of another diy check of the head gasket other than a trip to the shop? It does have an oil leak but when looking at that issue I found that most of the bolts to the rear of the pan were very loose. tightened them up and that seemed to rectify the majority of that problem although it does still leak a bit when parking on a hill with the rear on the down side. Thanks
 

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The leaking oil is nothing to do with a head gasket problem, thats down to fitting a new sump gasket.....as for the head gasket:

BY FOLLOWING THIS PROCEDURE YOU WILL BE ABLE TO IDENTIFY A FAILED HEAD GASKET.

1. OPEN THE BONNET AND WHITH THE ENGINE COLD CHECK THE COOLANT LEVEL AND COLOUR. IT SHOULD BE AT THE NORMAL LEVEL AND THE COOLANT SHOULD BE EITHER CLEAR OR BLUE OR GREEN COLOURED BY THE ANTI FREEZE, IT SHOULD STILL BE CLEAN AND CLEAR, THE INTERIOR OF THE EXPANSION TANK OR RADIATOR SHOULD ALSO BE CLEAN WITHOUT ANY SIGNS OF A SOAPY THICK CREAMY DEPOSIT. IF THERE IS A THICK CREAMY SCUM THEN THIS IS A GOOD INDICATION OF WATER AND OIL CONTAMINATION AND THE MOST COMMON CAUSE IS HEAD GASKET FAILURE OR A CRACKED CYLINDER HEAD. IF ALL IS AS IT SHOULD BE MOVE ONTO CHECK 2.

2. TAKE OUT THE OIL DIPSTICK, AND LOOK AT THE OIL ATTACHED TO IT IT SHOULD BE CLEAR OR BLACK, IF IT IS A CREAMY COLOUR THEN THIS INDICATES THAT WATER HAS MIXED WITH THE OIL AND THE MOST COMMON CAUSE IS A FAILED HEAD GASKET OR CRACK IN THE CYLINDER HEAD. IF THE OIL IS CLEAR OR BLACK MOVE ONTO CHECK LIST 3.

3. REMOVE THE CAP TO THE EXPANSION TANK AND START THE ENGINE, ALLOW THE ENGINE TO RUN UP TO NORMAL TEMPERATURE WATCHING THAT THE WATER LEVEL REMAINS CONTANT AND IS ROTATING AS IT SHOULD, REPLACE THE CAP TO THE EXPANSION TANK AND LEAVE THE ENGINE RUNNING, IF THE VEHICLE IS FITTED WITH AN ELECTRIC COOLING FAN ALLOW IT TO CYCLE ON AND OFF ON ITS OWN AND MAKE REGULAR CHECK ON THE TEMPERATURE GUAGE IT SHOULD SIT AT NORMAL SWITCH THE INTERIOR HEATER TO HOT AND TURN ON THE INTERIOR FAN THE HEATER SHOULD BLOW WARM OR HOT IF AFTER RUNNING AT NORMAL TEMPERATURE FOR 10 MINS THE GUAGE HAS STAYED AT NORMAL, THE COOLING FAN HAS CYCLED ON AND OFF PROPERLY AND THE INTERIOR HEATER IS STILL BLOWING HOT ON DEMAND TURN OFF THE ENGINE AND GO TO STEP 4.

4. ALLOW THE ENGINE TO REST FOR A COUPLE OF MINS, THEN WITH GREAT CARE AND WHILE WEARING GLOVES TO PROTECT YOU FROM THE HEAT TRY SQEEZING THE TOP HOSE FROM THE RADIATOR, IF THE HOSE IS SOLID THEN LEAVE A LITTLE LONGER UNTIL YOU CAN SQUEEZE IT A LITTLE THEN SLOWLY REMOVE THE CAP TO THE EXPANSION TANK OR RADIATOR, IF THE GASKET OR CYLINDER HEAD HAS FAILED THERE WILL BE A GREAT GUSHING OF BOILING WATER SO YOU MUST DO THIS CAREFULLY. STAND WELL BACK AND RELEASE THE PRESSURE SLOWLY, IF THERE IS NO GREAT GUSH A SLIGHT HISS, LIKE OPENING A POP BOTTLE IS OK BUT DO NOT BE TEMPTED TO DIP YOUR FINGER IN IT IT IS STILL VERY HOT. NOW CHECK THE OIL AGAIN AND THE COOLANT FOR CLARITY IF THEOIL IS CLEAR AND NOT CREAMY COLOURED AND THE WATER IS CLEAR AND THE ENGINE TEMPERATURE WAS STABLE AND NORMAL THEN THE LIKELYHOOD IS THAT EVERYTHING HEAD GASKET WISE IS TICKETY BOO.
 

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Discussion Starter · #5 ·
Thank You Very much. Did 2 of the 4 before purchase. Will try other 2 but am confidant you are correct that it is prob the osv's.

Would you happen to have the link that shows the process for replacing the Osv's? I found it when I first joined the board but have not been able to relocate the one that shows the v12.

Thanks again, I will sleep well tonite.
 

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Discussion Starter · #8 ·
You guys have been great. Thanks, but I can't find he OSV's (dunce maybe?). There is a cap with a sensor in it to the rear of each manifold (looks similar to the instructions link you gave me) but when I remove it, that's it just a sensor of some sort 2 inches long. I'm stumped, a cap with a gasket and a sensor no OSV and no holes for the boots into the valve covers. Valve covers are smooth all the way!

This is a 1991 750 il e32

Please Help!
 

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Discussion Starter · #10 ·
Thanks Marti,

Replaced valves and boots. All is WELL!!!! Like a sewing machine, WOW what a difference. Soooo smooth. I was a bit nervous when first completed smoke had continued to billow but it seems that was just a residual effect from before the fix.

I ran across another issue while under the wrench that you may want to share in the future. There is a vac. line that runs from underneath the MAF down the front of the motor to a valve of some sort (yea i'm a mechanic lol) and the hose connecting them was broken badly. The hose was actually so hard and brittle it wound break to pieces in my hand. So a quick trip to the auto parts store for some line and a little more wrenching and done!!!

Thanks, I can once again sleep well. For now that is.

JohnU
 
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