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[henryw]

guys the m20 is coming to the end of its life but i cant afford to put a new donk in yet. the oil is more than half way up the dipstick but it is still reporting that its low. When i topped it up with more synthetic oil. it stopped reporting it was low for a week or so and then it reported it was low again and its not leaking. Could this be a faulty sensor? My other concern under the rocker cover there is a ticking noise that I consider unusual DO M20'S JUST SOUND LIKE THIS?? or is there something wrong. I think it could be the valve lifters not lubricated well enough, the oil pump could be stuffed, I am not sure. This could be tied up with the false reporting. I am not 100% certain what it is all about any help would be most apreciated. Henry

[charliesmith]

Henry,

If you're not sure of the engine oil quantity, then start over. Drain that expensive oil into a very very clean pan. Count the quarts as you repour the oil into the engine. That way you can verify the known quantity repoured in against the oil dipstick level. It's that simple. The low oil level indicator is just that...an indicator. It's there to notify you to "check the oil level dummy". The dipstick level tells you the actual oil quantity not an idiot light. To keep adding oil above the maximum oil level is extremely unadvisable. (The BMW Dealership will love you though.) It results in the crankshaft being drown in oil and the crankshaft rotating counterweights and connecting rods thrashing in the flooded oil pan creating a foamy mess. This puts the engine at great risk of blowing out a front or rear crankshaft seal. Then you really have problems. Out comes the engine. Sounds like an intermittent oil level sensor.

In regards to the engine ticking. Start with verifying/adjusting the valve lash. Best to eliminate that possibility first. When you remove the valve cover you will find out if the valve train has been getting lubricated. Want to find out? Fire up the engine with the valve cover off. If the valve train has been getting lubricated correctly, your engine compartment should immediately start to look like the EXXON Valdez just took a crap in it.

I assume by the oil pump being "stuffed", you mean not working or not working properly. The oil pump is the heart of the engine. If it quits, you will definately know about it in about 10 seconds. Knock, Knock, Knock.......

[edjack]

Never saw the inside of the M20, but most 12-valve BMW engines use a spray tube between the rocker arms to lube the mechanicals. The tube is held in place via two bolts, front and rear, and runs almost the entire lenght of the head. The rear bolt (at least on the M30)is hollow, and feeds oil from the block to the tube.

This bolt loosens up, and oil feed is lost. If this condition is allowed to go on for an extended period, most of the internals will wear out prematurely. It can be secured with Loctite 242, but clean the oil off the bolt and threads.

The other problem is that there are soft aluminum plugs on each end of the rocker arm shafts. If one blows out (due to extreme cold oil pressure), you will lose almost all pressure in the engine.

One blew out on my car. It was in the front, and I was lucky enough to be able to press a new one in by using the cam gear as a lever fulcrum. As before, use Loctite, but 272.

[sailingphotag]

hey, after you check the valve clearance [do it stone cold,moter hasent run in 24 hours]then assume that the ticking you hear is "normal" for a m-20 i bettcha it has in excess of 150,000 mi, ive had/have several m-20s over the years and at around 150 they just wanna tick dont worry she will last at least another 150.I think its the wrist pins myself. theese moters are long stroke and someone who i trusted told me years ago that long stroke moters are prone to wrist pin prob....jeff

[henryw]

yep how did you guess 155,000 kms and she was built in '88.....thanks jeff

[edjack]

Jeff,

Why would a long stroke engine have wrist pin problems, say, over a short stroke engine? If anything, due to geometry of the con rod, and the angles it assumes, the wrist pin will see less rotation in a long stroke.

I would more suspect that it is piston slap, due to dragging the skirts up and down a long stroke. The pistons will cover a greater distance, mile for mile, than in a short stroke engine.

Remember also that this engine was the dreaded Eta engine, with low tension piston rings.

--- Ed Jacklitch


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[sailingphotag]

Hey, uh yea i hear what you are saying but...i took one apart a few years ago 300,000+ miles looked at crank wita dial indicator just as round as could be...piston skirts still had mill marks around em...and were still round one, thing caught my attention though ,theese pistons were heavy didnt weigh them but man they were thick and the rings were more substansial than the bmw replacements... the main and rod bearings were still withen spec [plasticguage]had the head apart cam bearings okay i meen what was left was wrist pins i didnt wanna spend the$ to replace the piston rod sets sooo put new bearings in moter, rings, honed er out ect and it still ticked....started asking around and someone i forget whom told me that this is common problem withh long stroke moters...seems like he said something about the force on the pistons being greater and now that i think about what you said "less rotation" now you have a bearing with the same or greater force working over less bearing rotation.....well lets not get into a pissing contest here... im just posting what someone told me and if youve read many of my posts you know i dont convince easly...maybe someone else hasa better answer. any takers?? lots of em do this ...someone smarter than me must know for sure and has solved this problem...jeff

[dale]

My theory on the tick is valve clearance due to valve stem being concave from much use.
BMP www.bmpd.com sells valve lash caps to give you a new surface to adjust from.
With a feeler gauge you are adjusting to the edge of the valve stem, but the follower rides on the center of the valve stem.

Dale
'86 325es with tick, former
'88 325is with tick, former
'89 325i with tick, former
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'80 528i
'86 325is #332 race car
'90 K75 RT
'01 Z3 Coupe
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