noise developed tonight at almost exactly 3000rpm

[f s t caz]

was out driving and boosting tonight, came to a stop light, and as i decelerated, i heard a rattling sound from the front of the car. Upon acceleration, nothing until about 2800rpm, and from then until 3100rpm i could hear a noise from the engine. I promtly pulled over and popped the hood. When i got within that range, i could almost always duplicate the problem. Checked the oil and it was low, so i babied the car home and added a quart of oil, which put it right in the middle of the dip stick. I've become more and more aware that my T28 is in need of a rebuild, but knowing that it has consumed over a quart of oil has me worried. The noise is still there even after adding the quart of oil. It sounds to me like it is coming from the upper half of the motor and I was thinking perhaps i collapsed a lifter. In reading up on it, however, it seems that lifters are problematic on cold starts, at idle, or at high engine speeds, and not within a narrow range in rpms. I read that a bad front main bearing knock will be most pronounced at 1500-2500rpm, but that's about 1000rpm too soon in the revs. I've never reved the motor past 7200rpm, and I do not believe i ever went above 7K tonight. Was i pushing my luck going that high? Am I looking at replacing lifters, or bottom end bearings? If i closely monitor the oil level, will i be safe to drive the car daily if it is bearings?

I've put ~2300km on the motor since installing it, and before starting, i filled the motor with 2.5 quarts of Mobil 1 15-50 synthetic and almost 1 quart of lucas oil stabilizer

A compression test done earlier this week showed 150psi across the board.

Also, can anyone vouch for cheapturbos.com rebuilds? Can anyone else recommend a good place to have my turbo rebuilt? Has anyone here had a good experience w/ a Rebuild kit?

Thanks for any input.Chris

[iliketocrash]

i'm curious to find out what this is. keep us updated on the situation. threads like these tend to die out and the problem is never resolved on the board and it just leaves me in perpetual suspence.... i hope i'm not the only one who feels this way...

[slw240sx]

eek lucas oil stabilizer is the devil.

sounds like big end bearings..

[Nismo1182]

YUP! Same thing my motor did.

[KaZ (VaBch)]

Bro, noise is just from 2800 to 3100? Can you define the noise a little better? I'm sure I'll take a listen to it tonight... just curious what it might be... We'll figure it out.

[boost_boy]

2800 to 3100 usually sounds like the rod bearings. Make sure oil is getting to your head! If your oil is not flowing, you will risk damaging your turbo as well. Definitely see if your oil is pumping and get back to us.

Dee

[f s t caz]

2800 to 3100 usually sounds like the rod bearings. Make sure oil is getting to your head! If your oil is not flowing, you will risk damaging your turbo as well. Definitely see if your oil is pumping and get back to us.

Dee

i can remove the oil cap and see oil being splattered around inside (and being tossed outside) the valve covers, so it seems to be getting oil. any other method for checking?

I took the car by the dealership and talked to my master tech. The first thing he said when he heard it was "it sounds like valves." He said the noise is definitely coming from the upper half of the motor, and that most likely, a lifter (or multiple lifters) went dry because of the low oil level. I asked if removing them and soaking them to pump them back up would work, and he said its worth a shot.

I'm looking at doing that this weekend, but still have the intention of pulling the motor in the near future to replace the bearings now that i'm all shook up and nervous, as well as reapairing the turbo,

[boost_boy]

People seem to make that assumption on this motor and it's usually the bearings, but I hope not in your case. The only reason why these lifters will make noise is because your oil pressure is in sufficient and the fact that very little to no oil is reaching your head. I would definitely get curious about the oil pressure 1st because when that goes, so does turbos.

Dee

[f s t caz]

figured i'd update.

still making the noise though the range has seemed to broaden. I took the car by another trusted mechanic and explained the issue before he ever set eyes on the car, then a few minutes later, he was admiring how smoothly the motor ran and when i reved it, he heard the noise and instantly said "yup, needs rod bearings." So, i've already planned to remove the motor and replace the main and rod bearings, but am still undecided about rings. i know my compression's good, but i also know i ought to do them anyways while i'm there. The only thing holding me back from doing it is that if i do, i want to get an ARP bolt kit which i can't afford right now.

I have also since bought and installed an oil pressure gauge. After starting, its ~40psi, lowers to 20psi when the motor has warmed up (fsm says anything over 11psi is good at idle) and its ~65psi at 3000rpm and makes it to 90psi under boost in the 6000rpm+ range. Is it safe to say that my oil pump is in good working order and thus i won't need to replace it when i do the bearings?

[boost_boy]

It is very safe to say your pump is up to par and working just fine. Keep this in mind, you're the 1st owner of this motor and probably not even the second. Every newbie around here think that they can buy this motor and start revving it right away; especially with no oil gauge or any other for that matter. Well, they can rev it to hell if they want, but it may have been wise for them to go out and buy a B16 or B18 if they wanted to rev to 9k. Rod bearings are fragile and the more you rev it and the higher you rev it, the more oil is squeezed from these bearings and risk of damage is always there for any motor including the little honda rev monkeys. Just get you a set of new bearings and don't worry about the bling until your money is right. And BTW, your pump is almost as healthy as the one in my G/Fs engine and it's been worked really hard for a long time;) .

Dee

[r34 gtr]

i got my t25 rebuilt at http://www.timsturbos.com and he will warranty them for a year. very good guy.

- tim

[S13 Charlie]

Dude! I have pretty much the same problem with my KA ('91 240sx). It happens on both acceleration and deceleration. Usually comes in about about 2800-2900 rpm, and only in that range. To me, it sounds like a resonance (vibration) in the heat shield. The fella I bought my car from said he's had it checked out and the mechanic couldn't find anything wrong. If anyone knows anything about this oddity, I sure would like to know what I can do to alleviate it.

p.s. This is my first post, but I've been checking out the CA forum for quite some time.. You guys are true car enthusiasts! I learn more in this forum than in the rest of the internet, hah!