W50-18RG rattle

[TA-022]

Well at the end of my Wakefield Day i noticed a tappy rattly type nosie coming from what seemed the engine bay.

Checked oil ...low. Ok probly lifters... oiled it up .. still noisy.

Noticed gears slightly harder to engage. Thought gbox / clutch issues. Suspected the clutch was always a bit average.

Take to clutch place Monday Arvo .... guy said if the clutch being pressed doesnt change the noise then its not clutch / gbox. He listened and said definately motor ... possible piston ring land and / or chipped valve if he had to take a guess.

Called mechanic mate in ... Compression test.. 130-130-120-90. Squirt of oil into chamber..compression jumps up to normal.

What is this likely to be (the compression issue) ?

Mate said cant tell until motor is pulled down.

Get to work this morning, idling in car park space... notice the sound at idle. Press clutch in.... no noise. So going by the old fella at the clutch place would one assume this rattle is a clutch / gbox issue?

Noise really is onlyaudible at about 2500-3000rpm in any gear. Gets louder and faster with increasing revs. Back off slightly on the gas and the noise stops until the revs drop to where you backed off too.

Now mate thinks thrust / spigot bearing?




Any opinions before i pull things apart... just need to know what im looking for / at?

Cheers

Nathan

(Sorry for the length but needed all the info out there )

[Norbie]

If the noise goes away when you push the clutch in, it's definitely not the thrust or spigot bearing. They are spinning when the clutch is in and idle when the clutch is out.

Nope, sounds more like you've got dud bearings in your W50. I'd advise you to check the oil level, you might find the rear seal let go at Wakefield and spat all the oil out. A similar thing happened to my W50 a few years ago and it started rattling badly until it died completely not long after.

[TA-022]

will do. as long as it turns out to be the box and not the motor ill be happy. easier to change and cheaper.

not at a point where i can afford to open the ol 18rg up right now.

Thanks norbie

[stradlater]

I know it sounds silly, but timing chain?

[thechuckster]

Chain rattle will usually manifest itself at idle or low rpms when the oil pump is not providing enough pressure to push the chain tensioners out fully.

cheers,
Charles.

[stradlater]

Was just a thought..

my 18rc would rattle all the time..
But, it wasn't long till it rattled it's way THROUGH the timing case.

[Celica RA45]

just watch the oil pressure ,it might have spun a big end .18rg in std form dont like going around race tracks ,most of the problem is the sump design having oil in the centre is not really good as under braking the oil shifts to the front and under aceleration the oil ponds to the back and you end up sucking air in

[The Witzl]

dont forget those long sweeping right handers!!

[Mr DOHC]

my gearbox si doing the same thing, make a hell of a racket in 2nd too

[jeffro ra28]

Checked oil ...low. Ok probly lifters... oiled it up .. still noisy.

well it definantly aint lifters in an 18rg...

Same thing happend to my t50. Sounds like you need new bearings or are up for a replacment box.

[TA-022]

timing chain tensioner was replaced 1 month ago (leaking) and chain tension checked by stewart wilkins rallying so I trust that is in order.

pretty sure its clutch / gbox related now.

checked oil today and replaced.... no change ... mate recons thrust bearing or dead/dying box...

gunna further inspect this weekend.

thanks heaps guys!

[barned01]

but why the low preasure in one combustion chamber?
maybe not related to the noise but still a noticeable difference to the other 3?

[TA-022]

always suspected a valve seat or something. No oil in water and vice versa but allways ran a little rough / lumpy on idle.

[Rodger]

I have the same problem with the T50 in my Three Tone Green TA-22 and also developed at Wakefield.

Rattle sound is there when in neutral and goes away when clutch is dis-engaged.

This is the sound most input shaft bearings make when on their way out. I have done two boxes in the past in my race car with exactly the same symptoms.

Regards

Rodger

[o_man_ra23]

Does sound like a noisy bearing... open up the box i say.

With your compression issues, it wont be a leaky valve, because when you did the oil test, the compression went back to normal, so its definitely ring related. I would say you have a badly worn ring (if its number 4 that is low) because number 4 always has the greatest amount of strain on it, as it is closest to the load (sounds a bit wierd in some ways, but its true), and number 3 has the next greatest amount of strain, hence no. 3 being low, but not as low as 4. Personally I would say replace either the bearings or the box, and rebuild the RG.

Cheers, Owen

[Norbie]

number 4 always has the greatest amount of strain on it, as it is closest to the load (sounds a bit wierd in some ways, but its true),

Closest to the load? That makes no sense at all!

You'll find cylinder 4 is most likely to develop problems because it's located at the hottest part of the engine. Think about how the coolant flows through the engine and you'll see what I mean.

[jeffro ra28]

funny, the number 1 cylinder in my experience with a bore gauge is always slightly more worn then the others. As its the coolest part

[Trent-KE30]

hmm good point you make there jefferson

[o_man_ra23]

Well, im not 100% sure exactly what goes on with it, but a good friend of mine who has been an engine technician for 15 years told me that one... personally i do trust his judgement (he is also a toyota man, makes him more trustworthy IMHO) Either way, ive found no4 to be the most susceptable to spun bearings and worn rings... maybe the bores dont suffer as much due to the heat, but the rings wear more.

Cheers, Owen

[jeffro ra28]

heh, 30 years experience told me the above one, and then backed up by another 13 years........

who knows tho. could vary i suppose