My engine has problems at Putnam this weekend. The valves, despite repeated attempts to set them properly, remain laughably adjusted. This low level but constant cacophany is now accompanied by a loud clatter but seems isolated to just a couple of cylinders and worst at light to moderate throttle openings. I managed to limp it back to the garage in Indy by repeated acceleration and coast down. A friend with many years of E30 experience and Skilled in the Art professed that it sounded to him like all top end noise. The Bentley description of crankshaft bearing problems “Crankshaft bearing problems produce a deep, hollow knock that is worst when the engine is warm.A noise that very pronounced under load, perhaps louder during the transition from acceleration to coasting, is most likely caused by a damaged connecting rod bearing,” sounds like a fairly close fit. I have not yet had a chance to install a baffle or scraper and ran an enduro on Friday and the usual race on Saturday. Any votes as to the noise source and do I dare run it on Sunday? I’ve already destroyed an S54 motor by voting yes to the second question before.
Dear Weird Engine Noise Fairy
I’d orient on the valve adjustment problem first. That could explain the noise making it unnecessary to worry about other issues. Fix that first, and once it’s fixed if there’s still clatter then worry.
So what’s with the valve adusters? You’re adjusting the valves but they’re not holding the setting? Or is it that won’t adjust down to the right spec?
Not everyone will agree with this, but IMO you’re setting yourself up for a bearing replacement. No scaper, no oil pan baffling, and no 20psi oil pressure switch to tell you what might be happening. It’s all just asking for trouble.
You’re at least running an extra quart of oil, right?
If it’s a rod bearing you can isolate the cylinder by pulling a spark plug wire. Pull each one in turn and when the sound goes away you found the cylinder.
Re. should you run it on Sunday. If the answers to the above questions make you think it might be a rod then I wouldn’t run it. You’ve years of racing ahead of you. One day’s race is meaningless. But if it is a rod bearing going bad and it fails at high rpm that could make a mess of your block and oil down the track.
If you think it’s a rod bearing isolate the cylinder, go home and pull your oil pan. Then pull off the rod cap and look at the bearing. If it’s worn you can do the ghetto thing and swap rod bearings in from underneath and call it a day…with luck you’ll get 2 more seasons before the main bearings go. Or you can pull the engine and do a full rebuild.
Note that OEM rod bolts aren’t reusable so you’ll need to buy some if you go down that road.
Thanks Ranger. just the kind of advice I was hoping to get. I just finished readjusting the valves again. Will see how it sounds. The reason I’m having trouble getting it right is going to sound stupid. It’s getting the gauge oriented properly in the cam valley to get a good feel for the “stiction” level of the gauge between the eccentric and the valve prior to tightening things down. I’ve tried three gauge sets and they all have size and/or geometry issues. I’ve run out of the gauge sets available at the local parts shops. This time I just put them all on the pretty tight side of 0.010. We’ll see how it sounds. The baffle and scraper issue is quite temporary, I will have it in before the next race. And yes, I’m running an extra quart. I had more or less already concluded that today was a wash, but maybe I’ll get lucky. My toasted front wheel bearing all came off in one piece yesterday morning. Someone is watching over me.
It takes some practice to do valve adjustments, can’t be helped. After adjusting it with a 10 and tightening the adjuster nut to less than full tight, try putting a 9 and an 11 into the gap. Sensing the gap with those two will create confidence that you’ve set the gap that you think. If you are comfortable that the gap is right, put the 10 back in and tighten to full tight.
Until I had done this multiple times I would check and recheck and recheck until I was absolutely sure each one was perfect. It took a while to do it that way, but that’s how you gain the experience and confidence such that you only need to recheck once instead of infinite times.
Get “bent” feeler gauges that have separate handles. They sell feeler gauge sets that have a couple handles included. This lets you pull the gauges apart and stick the two that you want on to the two handles. If you get two sets you get 4 handles. You want to end up with a 10 on a handle, a 9 on a handle and an 11 on a handle.
Here’s what I mean. http://www.amazon.com/CTA-Tools-A308-Offset-Tappet/dp/B006Z58ZJ2/ref=sr_1_11?ie=UTF8&qid=1336912102&sr=8-11
Still sounds like a can full of thumbtacks. Never had this much trouble with simple valve clearance before. Anyone know of any little tricks regarding the adjustment? Read something about flattened eccentrics. 0.010" cold is correct, correct?
Check my post above I added some content.
Cold at .01 is fine. There’s some contraversy re. the existance of a BMW TID saying do the intake a little tighter so some do.
If the state of wear of the eccentrics is such that you can get the gap you want, then I figure they’re prob ok.
I have a valve adjustment DIY here http://www.gress.org/Home/Cars/TrackTales/track_tales.htm
Handles? What are these handles of which you speak? All my sets are the foldout type with about 30-50 gauges in a bent steel frame. I have a bent set, which is what I’m using, but it’s too sparse on thin feelers. I’ve got a 0.010 and an 0.008. I’ll get something better tomorrow when things are open. I guess I’ll go drive around a while and see if I think I can make it back to the track (I’m in my garage at home about 60 miles away.)
Jury is back. Car is not trackworthy. Any idea how a weak or broken valve spring would manifest? Also sounds like I may be in for a tranny rebuild soon. Has this nasty grinding noise at idle in neutral with the clutch engaged.
Rod bearings can sound similar to valve clatter. The difference is that noise from rod bearings will increase with engine speed and that from valves usually doesn’t. A few minutes of checking with a stethoscope will tell if the noise is from the head or the bottom end.
I don’t recall that I’ve every read anything about weak or broken valve springs, sorry.
Re. tranny. Get your self a spare off some kid parting out their car. Drive yours 'till it dies, replace it with your spare. Maybe send the dead one to Andrew@Drivegear for a real rebuild.
Another way to distinguish rod noise from rocker noise is that rod noise should get worse with warm oil but rocker noise is pretty independent of temp.
Also, recall the bit about removing a spark plug to identify which rod bearing it is. Screwing with the plug wires won’t change rocker noise, but it will change rod noise, so that’s another way to discriminate.
The rocker noise is actually much better, just not satisfactory yet. Will try again with your write-up in hand. There are two cylinders that especially seem to defy all attempts, hence the valve spring question. The clatter noise definitely changes with oil temp. Not present on a cold engine, 10 miles later and it’s back with a vengeance. Also it’s harder to evoke with no engine load. Will dig out the stethoscope as soon as I get back out to Putnam to pick everything I optimistically left there overnight. Why does the spark plug trick work?
Think I now understand this and evidence continues to mount in “favor” of rod bearing failure. No spark, no combustion, no (minimal) bearing load. 1.5 hour enduro on Friday, practice/qual/race on Saturday, no baffle, no scraper, factory 8 psi sensor, I was practically begging for bearing failure. Can the bearings be replaced without dropping the whole front suspension and subframe? Or if one manages to remove the oil pan is there sufficient working room to handle a bearing swap? I’m considering the ghetto solution to get me through the summer with a rebuild during the off season.
Replacement of the rod bearings can be done just by lifting the engine. But a better job can be done easier if you drop the subframe. And it isn’t that hard to drop the subframe and suspension. You should install a scraper at the same time and fitting that will be much easier with the subframe out of the way. Use an engine brace to support the engine so you have clear access to the bottom end.
Something else to consider would be to get another engine to finish out the season while you rebuild this one the right way.
E30’s tend to be somewhat rare in Indy although they breed like rabbits over near Wright-Pat AFB which is a fairly quick trip. Any suggestions as to how to find a reliable replacement to get me through the summer? Assuming I can avoid some fatal “accident” when the CFO gets wind of plans. (No one would blame her, much less convict her.)
Re. replacing bearings from underneath. Rod bearings yes, main bearings no. If you use some platigage you could even do a test fit to reduce chance of surprises. Process:
Buy oil pan gasket, new rod bolts, scraper and one of the various baffled oil pan solutions.
Prob be best to drop front subframe like Jim recommended.
Pull off oil pan and oil pump.
Turn engine so that #6, or whatever rod you are most suspicious of, is at the bottom of it’s throw. Note markings on rod cap so you can put it back on the same way it cme off. Pull off rod cap and examine closely for wear. Note how tang on bearing is oriented on cap.
Examine crank journal for wear.
Turn crank a little so it moves piston up a little. Then move crank back a so a gap develops between crank and rod bearing top. With something non-metal poke at the top bearing shell so it will spin around crank and come out.
Take care that bare rod doesn’t contact crank surface.
If you want to plastigage before final install:
Take new bearing top, with no lube on it and spin it around crank so it pops into position in the rod. Put plastigage on crank. Put new bearing on rod cap. Fasten it into place with OLD rod bolts. Fasten to spec. Be very careful not to over do it. If you feel bolt starting to give, back off and pull the bolt out.
Pull rod cap out and measure plastigage worm against plastigage chart.
If you don’t want to bother with Plastigage, then just lube the new rod bearing halfs with assembly lube, put them in place and fasten up the rod cap with your new bolts. Do 6X.
It might not be a bad idea to pull a couple main bearing caps before you get too far along and examine them. If main bearings are showing wear, then pull the engine.
Re. another engine. I have a 92k mi bottom end that came from an automatic. That’s as fresh as it gets short of a new build. The head for it is in the shop getting refreshed. You could potentially buy just the bottom end or you could wait a week until the head comes back. It could probably be shipped to you for ~$150. Alternately, there will be folks from TN coming to CMP next weekend or RA next month. That’s a good fraction of the distance between us.
Did you check the oil for sparkles yet. I would think that no sparkles equals no bearing failure. I think I may have trashed my old head by continuing to run a motor with low OP and a pound of metal in the oil.
Nope, but good point. I think I may have lucked out and caught the failure early though. It may not have produced much metal yet. The thing I can’t quite figure out is that the noise seems to go away again under heavier throttle openings. It’s worst and loudest at the transition from 1/2 open to almost closed throttle.
Ranger, why not do the main bearings too while I’m under there?
Another stupid question, if the bearing(s) are worn enough to cause rod knock, why would a new stock bearing fit? Won’t I still have too much clearance? Wouldn’t this necessitate having the crank machined for an undersize bearing?
You have to measure the journals to see if they are worn too much for either of the two OE bearing sizes. If neither of those will provide the correct clearance or if the journal is worn out of round the crank would require grinding and over size bearings.