13 replies to this topic

[lrostoke]

Help please

Just measured the end float on one of our 998's

We are getting 0.20mm measured with feeler guages Haynes says 0.051 - 0.07mm

So I make that 0.15mm to much float

What oversize thrust bearings would we need. Do you double the size shown on the thrust bearing

eg thrust bearing says 0.003" oversize so is that each bearing ???

Which would be spot on 0.15mm = 0.006" which is more or less 0.15mm

cheers

[bmcecosse]

Yes - each thrust will be 3 thou thicker. Personally - I would just run it as is.....

[lrostoke]

I would but it makes a whooping noise yes a whooping noise.
And when you put pressure on the crank pulley nut when its running it stops, so obviously taking up the slack stops it

[bmcecosse]

Whooping noise ?? Oh dear.... Can't see why that would be for that tiny amount of end float...

Edited by bmcecosse, 16 October 2011 - 04:34 PM.

[sledgehammer]

I wonder if a bolt has come loose behind the flywheel ?
does it get louder when the clutch is in ?? (pushing the crank towards the radiator)
another thing - if the oil pickup pipe is bent , could it touch the crank ?
I doubt the cam chain would cause problems with that little bit of end float , unless the oil flinger ring is scraping the cover
sadly I don't think end float is the problem - but hoping for something cheap & easy
best of luck

[lrostoke]

Well the engines stripped, and the crank seems to move a fair bit to me, notable clunk when you push it back and forth.
No obvious signs of anything, clutch is fine. We took it out because we had what sounded like a tappet click, but nothing wrong with them, nothing under the timing cover looks out of place, and the noise sounded bottom end.
Big ends looks a bit scuffed but not massive wear but the crank did push back and forth a fair bit.
The end float was 0.3mm with the fitted thrust bearing, we stuck some new ones we had spare in and got it down to 0.2mm
Seems a fair bit to me seeing as the book says 0.05mm we are 4 to 6 times over

We know its basically a good engine we had it bored a couple of year ago and the crank ground pretty sure we checked end float then but maybe we mismeasured.

The tappet tick came before the whoop whoop so think all related.

Going replace the shells and thrust bearing whilst its stripped..

[sledgehammer]

I have a similar problem - got a 998 with heavy tappet (sounds half crank speed) - checked and replaced cam followers - set tappets-still the same sound
stripped engine - a bit of wear everywhere - but nothing looking obvious for the sound (cam is ok (used to work for k-cams))
the thing that annoys me is that I am replacing things I don't need to -just in-case
Keep in the back of my mind - 'it's a project'

[Cooperman]

The original BMC Workshop Manual gives 0.002" as the minimum end float. I usually aim for that as a minimum with 0.005" as a maximum on a new engine.

[lrostoke]

Well taking the original thrust bearing clearance of 0.30mm thats just under 0.012" so over double the maximum, so whilst its stripped won't hurt to get it back in tolerance

[lrostoke]

Quick update, finally got time to rebuild engine this weekend and refit, fitted 0.005" thrust bearing , crank is spot on now for endfloat

replaced big ends and mains for peace of mind.

started her up, good oil pressure, runs smoother than a smooth thing, and best of all, the noises have gone,

Bad news is checked rear brakes, needs shoes , not a big job, but found a hole in rear wheel arch..so looks like the welders coming out

[lrostoke]

I do not believe this car, cars done about 25 mile since putting it back together and the knocking noise is back.
It's weird. Its got new mains and big ends, crank was reground about 2 yr ago and looks fine, endfloats spot on.
cam chain all ok including tensioner,

about only thing not checked is little ends which were new with pistons 2 yrs ago, and cam followers.

[Pigeonto]

How are the idler gear and primary gear end floats? If they're helical they can knock when they have excessive float,especially when cold or on choke when the idle is a bit lumpy.

[lrostoke]

noise seems to be from timing chain side. Damned annoying engines been out and stripped and nothing obvious, only thing we didn't strip was top end and remove the pistons.

[sledgehammer]

some random things to check -

bent push rod / rockers worn , fuel pump arm bent / cracked / spring missing , valve spring weak , cam follower worn / sticking

warm up engine , disconnect fan belt

start engine and listen with a long bar against ear to various engine areas

press clutch - see if noise changes

I'm puzzled why the sound went away for 25 miles

what does it sound like with the filler cap off ?

... but hate to say , could be gudgeon pin fault / piston fault

pop head off if all else fails , & try to twist pistons / pivot pistons

Edited by sledgehammer, 23 November 2011 - 07:25 PM.