Jump to content
HybridZ

HELP>>>funny engine noises


Recommended Posts

HI All,

 

a guy that I know has just finished an RB26DETT S14 engine conversion. He is worried about some bad engine noises and would like to know what it may be. I am no mechanic but my guess is the main bearings???

 

It takes 3 to 5 min to download on a 56k dialup.

 

http://24.163.137.145/engine.wmv

 

Thanks,

 

Cuong

Link to comment
Share on other sites

The ringing noise at the beginning has me puzzled :? could be a problem with the starter or ring gear?

The knocking noise sounds like the rod bearings are shot. If so it going to need a crank,resized rods, and all new bottom end bearings, as well as a thorough cleaning.

Might be cheaper to get a reman short block in the end?

Link to comment
Share on other sites

I agree, that sounds just like some shot rod bearings. The puzzling part is the ringing noise at the end. Have him check the starter carefully. It might not be fully disengaging and might sound like that. Did he check the engine before he put it in?

If it is a bottom end problem, just new rod bearings might be enough to fix the issue depending on how bad the problem is. Re-sizeing the rods are usually a serious issue.

-Bob

Link to comment
Share on other sites

I`ve never been an advocate of only changing bearings. From my personal experience I`ve found that whenever you have a rod bearing failure, There is usually some other reason for the failure. Maybe low oil pressure, or maybe foriegn debrit in the oil.

Both of these can cause crank damage as well as bearing damage.

 

If you attempt to change only the bearing. Be absolutely sure that the crank is within specs for taper,diameter, and out of round. Also be sure that there are no visible marks or scatches in the finish of the journal.

 

These can usually be felt by dragging your finger nail across the journal to feel for scoreing or scratches.

If you feel any roughness, and have anything other than a smooth polished finish to the jounal, regardless of any other specs. I would recommend replacement or regrinding the crank.

 

the reason for resizing the rods after a bearing failure is...When the rod bearing wears creating enough extra clearance for the rod to knock,It can have a tendancy to warp or egg shape the rod end.

This can cause clearance issues that may not be detected by plasti guage, and could effect the proper lubrication of the bearings.

Link to comment
Share on other sites

Well put. I put " just new rod bearings might be enough to fix the issue depending on how bad the problem is.", but didn't elaborate. I.E. that was a best case scenario. I agree with you 100% and I'm glad you elaborated.

-Bob

Link to comment
Share on other sites

on a turbo motor rod bearings usually go from detonation that flattens the bearing and then it begins to spin. Definitely a rod bearing noise. DO NOT continue to run the motor like this. Debris can take out the cam lobes from clogging passages. The block should be completely disassembed and cleaned along with a thorough cleaning of the head. It is an awfully nice motor to do things half-ass! :lol:

Link to comment
Share on other sites

That ringing noise is no doubt the starter/flywheel messing around in that tranny case. Sounds identical to my IROC start problem.

 

The knocking noise could also be the valves hitting the pistons. Anyone else notice the rough idle? Its for sure not timed correctly.

Link to comment
Share on other sites

Stupid question... my research on some of the JDM engines has found a couple of different places noting that you always need to check the oil pan to make sure it's not been dinged. Apparently the engines get tossed around a bit and the oil pan can get dented upwards such that it either blocks the oil pickup or can actually bang the crank (did this on a SBC once). Migh tbe too late for this motor but posisbly something worth checking - especially if the pan isn't cast aluminum. Is the RB motor using a cast pan? :?

Link to comment
Share on other sites

Guest Anonymous

As for the squeek or shrill in the beginning that is the starter. I would imagine that the car has a twin plate. SR's do that alot if you install a twin plate yet forget to make a spacer for the starter. As the twin flywheel is thinner and is a tighter fit to the engine than the stock flywheel. (depending upon the brand) (Clearance from rear of flywheel to rear of engine is diminished) Requires a 2-5mm spacer be fabricated. Here in Japan they just cut the spacer out of some 35-40mm aluminum piping and place that over the ring gears for the starter. So it rests between the starter and bellhousing when bolted up. The starter edges no longer sit flush on the bellhousing. This allows it to withdrawl fully when dissengaged. Or there are parts stores here that sell a sexy little aluminum spacer for about $80 bucks..

As for the nasty rat a tat, tat.. Noise coming from the engine. I would agree with the majority consensus that it is more than likely the bearings.

(However I noticed that he put the HKS cam gears on the motor), How far down he broke the motor before installation would help out. Do you know if the noise is coming from the head or the Block? (stethascope)

RB26's are real picky about valve clearance.. If he broke it down to far, removed cams, or switched shims, or even forgot them, or did not torque the cams down right.. You could have slap with valve and pistons, or a slap between the valve lifter and the retainer/ top of valve.. Or he could have the cam timing out of alignment creating another possible clearance issue by having not started out at TDC. The clearance between cam and lifter is only .45mm (intake warm) .38mm exaust (warm) or .51 and .44 cold. Which aint alot and it's easy to Fuzz up if taken apart and not put together correctly.

Another quirky thing with R motors is that when you throw a rod bearing it is usually #2, and #4. Very seldom is it just a one bearing event. It's also accompanied by a grinding, screaching sound.. As the stock bearings have a tendency to dissenegrate and pieces roll around inside the block. Creating clearance issues with things they should not. Drain out the oil and look for little dull silver pieces of metal fleck or big chunks in it or check the oil filter very closely.. I've blown up a few GTR motors and they all seem to go out the same way.

Did this happen suddenly under boost? Looks as though he is running in the T04S, 78 or T51k catagory and that would do it.

The quickest way I've found to destroy and RB26 is bad vavle/ignition timing and boost..or creating a lean fuel condition. On a stock bottom end 1.3 Bar is safe W/enough fuel..above that you start cutting down the motor life.

It's kinda hard to diagnose via video, but this is just my two cents on the issue.. check the head first and the oil, find out what cicumstances this appeared under, and what he was boosting..

Link to comment
Share on other sites

OUCH!!!!! I would guess that motor is history and in need of a complete rebuild. it also sound like the turbo blades are rubbing against something as its spooling down. but at any rate that motor sound like crap. sorry... was that a motor bought from an importer or something that just broke?

Link to comment
Share on other sites

My diagnosis is;

 

1. Loose or wrong cam drive chain. On accelleration the chain is balooning out and rubbing the cam cover.

 

2. The cam itself is thrusting forward and scrubbimg the cam cover on accelleration.

 

3. Both conditions may be occurring at once.

 

4. I pass on the other noises...LOL. (Get a mechanics stethascope and search them out).

 

P.S. : For the ringing' date=' look to the ring gear on the flywheel skimming the starter gear. Space the starter assy. 50-100 thou. further out from the housing. (My God what a racket...LOL)![/quote']

 

None of the above. the RB dosnt have a chain....and you can see the front cam cover is not even installed so it cant be that.

 

It sounds very sluggish.... i would guess its dropped a couple cylinders also or maybe a couple fouled plugs. Mine... even with the turbos not plumbed in... has quick throttle response.

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

×
×
  • Create New...