Oil pressure issues and the Regs

#41

I was looking at some info on E30tech dot com and noticed this:

Crank Rod Bearings** */ Crank Main Bearings *** -These should always be replaced; upgraded coated race bearings are available depending on intent of the rebuild. BMW changed the design of the bearings in later M20’s so be sure you get the right ones.

Can anyone here verify if this is true (and if it is, what change was made)? I would imagine it would booger things up if you used the wrong set. Were all the blowed-up rebuilds we are discussing done by true BMW rebuilders who would know this kind of thing?

Ranger wrote:

[quote]1) Allow 360deg cut in main bearings.
2) Allow coated bearings.
3) Allow remote oil filters. This makes it easier to change filters, add sensors and an accusump. Make something easier and more folks will do it.

Someone tell me why those rule mods are a bad idea.[/quote]

  1. Don’t know if this will help. It seems logical, but I don’t see it on Korman’s laundry list of ways to pour good money into an M20 engine.
  2. Seems like a good idea (provided the failures are not caused by something that can eff up coated bearings, too)
  3. The only downside is more plumbing to potentially fail. I like the filter sandwich plate for its simplicity, but it would be nice to have the filter somewhere easier to access.

Steve D.

#42

mikeski38 wrote:

[quote]
Careful with the 360 degree cut thing. The reason why the top bearing is flat is to allow for the buildup of a thicker boundary layer of oil since the top bearing sees more load. If you remove surface area, you will decrease the thickness of the boundary layer and wear your bearings faster. and it is a performance advantage because now that bearing has a lower rotating resistance due to the smaller boundary layer. If BMW wanted a 360 ring there, there would be one. I would imagine that the BMW design engineers had more experiance with this sort of thing then we do, it would be a long shot to say we could redesign their motor and make it better. There is a something else going on here, not a design flaw in our motors.[/quote]

I looked at my bearings this morning. If I recall correctly there already a 360deg groove in the main bearings. I think that the cut (that improves oil supply) that I was told about is actually in the main cap, not the main bearing.

I’m not saying there’s any design flaws. I’m saying that the motors were not designed for how we’er using them. If you make something more robust then is likely necessary, you make it more expensive then necessary. Engineers calculate strength and durability, throw in a safety factor and then move on. But when you calculate strength and durability you make assumptions about how the part will be used. This block was designed when, early-mid 70’s? Hermann the German didn’t plan for NASA SpecE30.

#43

While the car and engine wasn’t expressly designed for road racing, I don’t think it would be a stretch to say that it was designed to survive the Autobahn. That is probably about as stressful as what we do with the cars.

#44

The change in bearings was simply a design change in the number of tangs. In '88 they went from a single tang design to the two tang version (I think, I’ve been inside too many of these motors recently). They are interchangeable one way, but not the other. Also, I believe the SETA cars were the only ones to get a full oil groove. Half, full, and anywhere in between oil grooves have been debated for decades. It really just comes down to the engine builders preference. Running a full groove is not going to be the magic solution here. Yes, you will have more oil present in the bearing/journal interface; in exchange for higher loads on the bearing from the decreased surface area. PRESSURE will not change as it is dictated by the pressure relief valve.

Like the kid someone on here said they met at CMP, I’m running my way through the ranks of DE’s, and I’m about to be on engine number 5. One bum motor from Molitor, and 3 bearing failures. One of which was a .010/.020/.020 ground crank with oversize bearings, and a new oil pump. The latest of the bunch to fail was at Road Atl in March. It was also the first time I’ve had an oil pressure gauge in the car on track. By the end of the day Sunday, I was seeing 0…yes ZERO oil pressure through 5 and 10a. And around 20psi through 4/top of the esses. By the end of the last session, I was seeing less than 50psi down the back stretch, whereas Sat I was seeing ~65 psi…on the pressure relief valve. Then, sure enough I found metal in the oil after the last session Sunday. All my motors have had 15w50 Mobil 1, filled 1/2 to 3/4 qt. overfull. I believe the issue to be oil starvation, and nothing further.

I’ve since bought a 3qt Accusump with manual valve, and a crankscraper which will be installed in my new (used) engine before Barber at the end of the month. Hopefully the car will FINALLY survive a single weekend without finding metal in the oil.

Check valves and Accusumps… The Accusump check valve has a cracking pressure of 5 psi. No thanks! However; Earl’s makes a valve for 1/2 psi pressure. I have a friend with one on his m20, and it seems to be the ticket.

Some thoughts on oil. I’m sure most of you know, a few years back the EPA effectively removed some additives (most importantly Zinc) in our oil that is not really required for newer vehicles/valvetrains. It builds up in the Cats and kills them… Diesel and racing oils are the only ones left with the good stuff in them. However, running a ZDDP, or until discontinued GM’s EOS will get the additive levels back where they need to be for our solid cam, dinosaur engines. With modern oils, you pretty much have to run EOS or equivalent in any mechanical/solid cam engine during break-in. Zinc is a self-sacrificing metal that helps protect the camshaft until properly broken in. But, with it being removed from modern oils, it’s a good idea to run these additives all the time; basically bringing the levels back to where they were a few years ago. Ever see a lifter or rocker arm wipe out a brand new camshaft and want to know why?..

nonetheless, I don’t believe the type of oil, additive, oil groove, or coatings someone may or may not be running to be the issue here. I’ve kept some pretty stout turbo motors alive on regular 'ol Castrol 10w30. I think (at least in my case) that it is simply oil starvation…and an Accusump should be the solution.

#45

Good points.

I’m going to connect an Accusump to an oil filter sandwich. I think that means I don’t have to use a check valve. I thought about connecing it right to the oil galley, but I couldn’t find anyone comfortable to drill into it.

Good point re. ZDDP. I did a bunch of research on oil last year. I learned that everything I thought I knew was wrong. It’s silly to choose an oil based only on it’s xxWxx manuf viscosity labeling. That’s a good reason to go with Redline oils. As I recall they aren’t API certified and therefore aren’t attempting to follow the emission controls requirements that mandate lower ZDDP.

I think that AMSOIL runs higher ZDDP too.

I’m redoing my gauges and sensors. I’m going to add some oil pressure warning lights. I’m leaning towards 30psi amber and 20psi red.

I’m interested in seeing if the oil ever dips below 30psi on the track. I’ve never noticed it dipping in sweepers, but I also wasn’t looking at the oil gauge at the time.

I found that they make aftermarket Heads Up Displays. Pricey but cool. They also make little warning lights that you can put in your helmet. Spiffy, but over the top.

#46

An Accusump will always need a check valve, otherwise when it discharges it will send some oil backwards through the pump/sump.

Sandwich type plate will work, but I will be tee-ing into the oil system at the rear most stock oil cooler line.

#47

Hey wstukas,

I’m the guy who has blow 5 motors. It sounds like we are having very similar problems. Have you made any other modifications to your car besides the engine? For example: Transmission, differentials, transmission or engine mounts, pressure plate, clutch, thrust bearings, or oil coolers? I’m just looking for a common thread.

Most of my engines are not even lasting 1 day at the track:

Engine 1: 1.5 weekends

Engine 2: 1 session

Engine 3: 4 session

Engine 4: 4 laps

Engine 5: 3 sessions

After the 1st engine failure, I drove these engines with extreme care. Most of the time I was shifting at 5K just to be safe.

Thanks!
John

#48

What was the hot idle and 5k rpm oil pressure on these engines?

#49

All my motors had the same new clutch, solid trans/engine mounts, different oil cooler “hats”, with the same cooler which was flushed out each time. I’ve yet to make it through a weekend with an engine…bummer. :frowning: I don’t believe it to be a trans/clutch balance problem. With my solid aluminum mounts, I’d feel if an engine were out of balance.

Jeingold, you asked about thrust bearings… like the thrust surface that is part of a main bearing in the engine? Then yes, one of my motors had new bottom end bearings with an undersize ground crankshaft.

Jim, I only had a gauge on the last motor, but hot idle off track before I saw any metal in the oil was around 15-20 psi. anything over about 4k rpm it was at 65psi.

after metal appeared in my oil during the last session, off track hot idle was at ~5 psi, and max pressure I could make was just under 50 psi.

I know I began that last weekend with a good engine. People keep telling my that m20’s are bulletproof…hmmm, I’m beginning to doubt that. It’s definitely no small block Chevy :stuck_out_tongue: .

#50

John, are you re-using the same oil pump and/or pickup? Do you have a gauge on the car? If so, do you see a drop in pressure anywhere?

#51

Maybe the solid engine mounts are the problem? I’ve heard the little bit of compliance the hard ones have is a benefit over solid metal (which aren’t’t SE30 legal, are they?).

Steve D.

#52

[quote=wstukas]Jim, I only had a gauge on the last motor, but hot idle off track before I saw any metal in the oil was around 15-20 psi. anything over about 4k rpm it was at 65psi.

after metal appeared in my oil during the last session, off track hot idle was at ~5 psi, and max pressure I could make was just under 50 psi.[/quote]
That was certainly enough oil pressure and indicates that the engine wasn’t suffering from a general case of excessive bearing clearance. Though it could be that one bearing (the one that failed) had excessive clearance.

Did this engine have a crank scraper? On the engine that had the reground crank, where the bearing plasti-gauged to geck clearance?

#53

as jim levine can atest to this. i spun the bearing in my spec at barber’s while jim was behind me. i bought my car for $6,500 full race prepped and ready to go with the stock motor from 87 still in it. I didnt have a scrapper or a baffled oil pan. It was great for a DE weekend at Barber’s and then at the PBOC on the 4th lap or so it spun the main bearing. Now with my 6,500 purchase i got a spare motor with 100,000 on the clock. I am now having to use it and put a crank scrapper in. But that is another $1,500 to add in plus i will have to build the one that is coming out. I am a decent wrench turner but i lack the facilities to do major work myself. So at what point do we still call it grassroots low dollar racing? I work paycheck to paycheck and i can’t just up and pay 1,500 every few months. the future better half would cut my parts off!!!

#54

theironman9154 wrote:

Racing is expensive, have you tried other racing? I used to race an E30 M3 and you should try rebuilding that engine (S14). Add another 3-4K a year just for tires (Hoosiers). You get the idea. It sucks when you have to rebuild a motor but I’m glad its an M20 when it comes to that time.

#55

I’m not saying there CAN’T be a problem, but I would like to see the number of bearing-related engine failures that tick all the boxes:

  • under 200,000 miles
  • crank scraper trimmed and installed per instructions (no debris)
  • oil pump replaced
  • heavier oil in older motors
  • oil temp and pressure gauges installed and monitored
  • engine assembled by the factory or an experienced shop
  • SE30 legal motor mounts
  • fresh guibo/vibration damper thingies
  • oil level between marks on dipstick
  • oil level checked each session
  • new flywheel bolts (if removed and reinstalled)

We’ve heard a lot about on-track engine failures and they seem to get lumped into the “oiling problems” category, but I haven’t heard what the post-mortem analysis on each engine was.

Again, I don’t have an agenda either way. If there is a problem I would love to help us have the cheapest, easiest solution possible. I’m just not convinced there is a widespread occurrence of bearing failure when all the preventive measures listed above are taken.

Steve D.

PS - On a $-to-lap-time chart, this is incredibly cheap, close racing. You can get cheaper, you can get closer. But SE30 seems to strike a nice balance.

#56

Well, one of my other cars (the one my father takes to the track) is a 1990 M-3 with a S52 out of a 97 M-3 and a 97 trans with the ODB1 system. I have problems with it as well thet no one can seem to figure out how to fix it. If the car is not all the way full with gas then the car wants to cut out like the pump is not pumping. We have checked EVERYTHING that we can think of. We even put in the fuel starvation kit from Turner and it didn’t help. So I know what you mean. Plus even with double adj. the car handles like crap and it has an E-36 Brembo big brake kit up front and e-36 M-3 brakes out back with ferado pads and it brakes like crap. I can turn 10 sec. a lap better lap times at Barber’s in my Spec then my father can in that thing. AHHH the ghostes in the damn system.

#57

Steve D wrote:

[quote]I’m not saying there CAN’T be a problem, but I would like to see the number of bearing-related engine failures that tick all the boxes:

  • under 200,000 miles
  • crank scraper trimmed and installed per instructions (no debris)
  • oil pump replaced
  • heavier oil in older motors
  • oil temp and pressure gauges installed and monitored
  • engine assembled by the factory or an experienced shop
  • SE30 legal motor mounts
  • fresh guibo/vibration damper thingies
  • oil level between marks on dipstick
  • oil level checked each session
  • new flywheel bolts (if removed and reinstalled)

We’ve heard a lot about on-track engine failures and they seem to get lumped into the “oiling problems” category, but I haven’t heard what the post-mortem analysis on each engine was.

Again, I don’t have an agenda either way. If there is a problem I would love to help us have the cheapest, easiest solution possible. I’m just not convinced there is a widespread occurrence of bearing failure when all the preventive measures listed above are taken.

Steve D.

PS - On a $-to-lap-time chart, this is incredibly cheap, close racing. You can get cheaper, you can get closer. But SE30 seems to strike a nice balance.[/quote]

We’re never going to get that kind of detailed data. I checked every single of your blocks except no oil temp gauge. But I’m just a single data point. But that all misses the point…We’ve had enough bearing failures to know that there are issues. There is no common thread like “they were all old bearings”, “not 1qt high on oil”, “no crankscrapers”, “it was installed by a wanker”, etc. But we don’t need to establish a common causality thread in order to accept the idea that there is a problem.

Look at it from perspective of someone deciding on which series to enter. Is someone who is looking to build their own race car because they are tight on cash going to note that older motors tend to fail with bearing problems? That potential newby could see that problem as a significant discriminator for choosing a series. And if it’s serious to the potential newby, the problem needs to be serious to us.

So lots mod the rules to allow some changes that “might” help. I came up with a couple possibilities a couple pages ago.

#58

Ranger wrote:

[quote]But we don’t need to establish a common causality thread in order to accept the idea that there is a problem.
[/quote]

There are problems. However, we DO need to establish common causality to accept the idea there is A problem. One of the ways to make racing even more expensive is to throw parts at a poorly-defined problem.

I would argue that permitting non-factory bearing grooves, allowing remote filters and plumbing, and implying that an accusump is necessary will NOT NECESSARILY decrease the incidence of failures and WILL increase the perceived cost to build a competitive car.

Steve D.

#59

I’d argue that bearing failures in Spec E30 aren’t any more common than rocker failure. Both occur, but not on a regular and frequent basis. If either were frequent, half the field would be down or absent on any given weekend.

it is probably safe to say that most of us are running engines of unknown history, either the one that came in the car or a junkyard motor. So past abuse could be a factor in those engines that have bearing failure. A properly fitted crank scraper (I favor the IJ design) should be sufficient to maintain oil pressure in left handers if the oil pump is good and the engine has sufficient oil. In my mind an oil pressure gauge is an essential piece of equipment and it needs to have a fast response time so as to track transient events. A lot of electrical gauges have a very small port and are more damped that is appropriate for racing conditions. Opening up the port can improve response time. Or you can use a mechanical gauge.

If you have a TracMate in the car, adding oil pressure to the logged data should reveal whether you have a lubrication starvation issue.

#60

I would like to add a few other pionts of data to consider

  1. has oil pressure loss been verified by a mech. gauge
  2. when bearings are replaced in the car , how was the crank clearance measured???, it wasn’t because it cant’ be done with crank in the engine( plastic gauge isn’t acuarte enough)
  3. not knowing crank clearance means you did not fix any thing, IT is a band aid. If you are replaceing bearings in the car , chances are it is becuase you had something knocking??Sometimes if your lucky just replaceing the bearings works, but, if bearing have gone bad, more than likely something is no longer round!!!
  4. where the mains replaced?? doubtfull, becuase the top half can’t be done with crank in the car! I have even heard of guys just doing the botoms on the rods,

Honestly , if you find something out of round /clearance wrong a m20 block ,it isn’t worth fixing because you can find another for next nothing!!

Why bother with an acusump,or ARP rod bolts( are they legal any ways???) if your not going to bother setting the crank clearance???