'94 325i Sedan, Arctic Gray: UUC LTW FW, EVO 3 and DSSR, +.020 Maxsil pistons, ASC delete, Eibach shocks/springs, 16" contour reps 238k
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'89 325i Vert, Alpine White: 5spd swapped. Sold
'04 Toyota Sienna XLE Limited AWD, In progress swapping to M50/G250, http://www.wibimmers.com/board/index...nna-25i-build/
'05 Volvo V70 R, 6mt, mostly stock, kid hauler 200k Sold
'85 Toyota LandCruiser: Lifted, gas hog. 205k
It is at the machine shop right now. He says that the scoring on the cams is not good but he has seen worse and will check out the bottom end with the valves, seats, guides and seals. Based on my experience with compression and leak down tests I think that the rest of the head will be OK once
the spring has been fixed but he might recommend some refreshing. I think if I could find a decent set of cams and trays it would all work.
Did you ask if they are familiar with BMW heads? because they need to know where they typically crack and warp so that they check for those things.
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yes he is familiar with bimmer heads
I am wondering if I need to look into the cause of the broken spring. Fixing it is not a big deal but I wonder what caused it and if it might happen again. What do you think?
Over reving the engine. Have you ever money shifted? ie. missed a gear.
But I would assume a manufacturing flaw would lead to failure as well.
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No money shifts. I was teaching a kid to drive a standard about 2 months ago and he hit the rev limiter once bit it ran fine after that.
-Josh: 1998 S54 E36 M3/4/6 with most of the easy stuff and most of the hard stuff. At least twice. 271k miles. 1994 E32 740il with nothing but some MPars. 93k miles.
Hitting 6500rpm redline while accelerating normally shouldn't cause a spring to break, I'd think (otherwise virtually everybody would have broken springs). It can of course happen, but it would be a case of very bad luck.
A wrong downshift where the engine would rev to say 7000 rpm for a short while, that's something different.
Last edited by ed323i; 09-22-2018 at 07:42 AM.
1997 E36 BMW 323i (European) 275k km (171k miles), with following small mods:
- Chip tuned DME (190HP/257Nm); 328i dual pipe exhaust (plug&play); Meyle HD control arms, Bilstein B4 shocks
- Fan delete mod: Stock 92C thermostat, 80/88C temp. switch, 80/20% water/coolant; INPA says temps 100% OK
- Throttle body coolant hose delete mod; Comprehensive ASC Delete option list; Solved: -30 additive adaptation values
I don't abuse the engine and actually don't drive it very hard. Maybe I have a bit of fun on on/off ramps and hit a bit speed on route 95 but mainly I have it because I like the open air motoring experience. I have never hit 7K during a downshift and I am assuming the rev limiter would take of that.
I think it was just a case of bad luck.. Metal fatigue or something.
Please note that the rev limiter only helps when you're accelerating. Once the rpm hits 6500 rpm, the DME will stop injecting and stop sending a signal to the coils..
If you do a bad downshift, the rev limiter does nothing at all to prevent damage. The only thing that saves you from major damage is quickly pressing down the clutch pedal before revs go over 6500 rpm (the engine should take a few more revs for a short while, so there is a bit of margin, but over 7000 rpm it gets problematic very quickly). For example, if you drive +/- 100 mph in 3rd gear (+/- 6500 rpm), and you shift into 2 instead of 4, the engine is toast (unless you un-clutch very quickly when you feel the revs go too high). In 2nd gear, at 100 mph, revs will be at 10,000 rpm more or less. Nothing the rev limiter can do to prevent the damage, as the revs follow automatically due to the rear wheels rotating at a certain rpm, which are then transferred to the engine through the axles, diff, propshaft, gear box and clutch. Stopping the injection and spark plugs from firing won't change a thing.
1997 E36 BMW 323i (European) 275k km (171k miles), with following small mods:
- Chip tuned DME (190HP/257Nm); 328i dual pipe exhaust (plug&play); Meyle HD control arms, Bilstein B4 shocks
- Fan delete mod: Stock 92C thermostat, 80/88C temp. switch, 80/20% water/coolant; INPA says temps 100% OK
- Throttle body coolant hose delete mod; Comprehensive ASC Delete option list; Solved: -30 additive adaptation values
Thanks for the very interesting information. I really don't think I ever did anything to cause it.
And usually money shifting will bend a lot of valve, so your right you probably didn't do it. )
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Yes I was relieved to find a broken spring but no sign of valve to cylinder contact.
sharadn, I'm not sure why everyone else is stuck on an overrev. Redlining it ONCE - and at 6500 no less - doesn't come close to counting.
So many people have their cars chipped to redline at 7000, and then proceed to redline them regularly (and I'm among that group).
Hitting the limiter at 6500 - once - could not be more of a non-event.
This is nothing more than a fluke. There's no blame, fault or error.
I had a valve seat crack and fall out of the head on my Escalade a few weeks ago. Machine shop said he sees it all the time on Hemis, but had never in his life seen it on a Chevy motor. It was just a fluke.
I'd be relieved you found the problem - and before additional damage was done.
I'd get a new spring, have that valve checked, all the guides replaced, and I'd find some S52 cams for it.
Anyone have a sourcer for guides and springs. My machine shop cannot get hold of hi's usual supplier.
Pelican parts as well as RMeuropean have both.
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Yeah duh, don't know why I did not think of Pelican. I called Bavauto and they could not supply the guides. The shop is recommending that I replace all 24 valves. I am wondering if it is necessary. This is the first time in my entire life I have had broken valve spring in any car. The shop says that it is so much work to change the head that it makes sense to change them while it is out. Opinions?
Parts Geek has them also
If they're not bent or chipped. Do they know this isn't going to be a race car lol.
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Parts Geek has them also
- - - Updated - - -
My bad, I was typing too fast and should have said that the shop wants me to replace all the springs not the valves.
Valves didn't make a lot of sense to me. I'm still not sure springs make sense unless he's assuming you thrash it all the time and that's why that one did break.
When I had my head done we replaced the valve guides - that's it. Yes, everything was out, but the other parts were fine.
Did he say why he wanted to do it (aside from the "while we're in there" argument)?
-Josh: 1998 S54 E36 M3/4/6 with most of the easy stuff and most of the hard stuff. At least twice. 271k miles. 1994 E32 740il with nothing but some MPars. 93k miles.
The shop is saying that something caused it to break and that all the springs came from the same batch. He says pay me now or pay me later. I talked the BMW mechanic that services my fathers car for a long time now and he says that he has never seen a broken valve spring. It is $354 for a set of springs so it something to consider. The car is 20 years old. Not worth much on the market but worth a lot to me in terms of usage and fun. It is a lot of work to pull the head and all. I will still talk to few other mechanics and see what they think but any other opinions are welcome.
I just bit the bullet and ordered all new springs. Wow this gets expensive to fix one broken spring. 575 for machine shop, 535 for new head parts 150 for head gaskets around 125 for tools. Closing in on 1500 and that is with me doing the labor. Still waiting to get a cost on a good set of cams and lifters. At lease when I put it back together I will know it is good. Whew....
Last edited by sharadn; 09-28-2018 at 03:33 PM.
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