22 replies to this topic

[lambretta]

Hello all.

 

We rebuilt a 202 about 5000km ago for installation into and old Land Rover series 2a.  All new bearing shells (but for the camshaft) and it was is running fine but recently it has developed a knock/tapping noise after start up.

 

If engine is left overnight on start up it is tappety for 2 or 3 seconds and then that goes away (assume its the hydraulic lifers getting to pressure) and the engine is lovely and quiet.  After perhaps 1 minute a knocking noise starts which is louder in the cabin than the engine bay.  It changes speed with REVS but doesn't come and go when the engine is revved.  Eventually, once the engine gets a bit warm its stops, happens exactly at same point on the temp gauge and ceases almost instantly - running time to noise stop is dependant on temp so if its cold you drive longer with the knock.  Has been doing this for 6 months.

 

Recently the noise has become louder and over the last few days there has been a couple of instances where the knock returned again within a minute of stopping but then disappeared again as normal

 

Using one of those stethoscope type things on the top end I can't pin point the noise there (although it seemed louder when listening to the thermostat housing).  Last night I crawled under the engine when it was still knocking and, using the stethoscope listened to the underside of the sump,  It sounded a bit rumbly and I could hear the knock down there no problems - seemed to get louder towards the front of teh engine.

 

I recall when rebuilding the engine the crank was very very hard to turn once the big end caps and rear seal was in place - i had to put an extension bar in the balance holes of the crank web to get enough leverage to turn it. I checked the clearance of the bearings with plasti-guage so perhaps that is a normal 202 thing, assembly was done with the assembly lube goo.

 

We are close to biting the bullet and ripping engine out of car to pull apart and inspect to see what the problem is but wonder if there could be something simple wrong o check before doing so.  My thinking is it's the bottom end (mains or big ends) but before I go to the drama of pulling the engine out I thought I would ask this experienced group their opinion.

 

Cheers

M

[RallyRed]

Dunno, but reckon I'd be removing the oil filter and cutting it open ( tin snips, not hacksaw or grinder) and laying out the filter element, looking for bearing metal. If none, then not that?
Only cost you a new filter.

Edited by RallyRed, 11 October 2024 - 02:23 PM.

[S pack]

I'd also check the rockers and lifters for wear, damage or failure. Esp cyl #1 & 2

[Bruiser]

Could be piston slap, once the engine is warm the and pistons heat up it can go away
I don’t think big end knocks go away when engine is warm
Have a bit of a Google and see if anyone else’s symptoms match yours
If your plastigauging showed good clearances
it could have been the rear main seal
rope ones are bastards and can be a bit tight

[Shiney005]

Can you get to the flywheel bolts to check they are still tight?

[rexy]

Manual trans?

 

If so I would be checking clutch and flywheel aren’t loose.

 

Weird exhaust knocks, loose engine mount and wobbly front pulleys are all on the easy to check built low probability list.

[lambretta]

Dunno, but reckon I'd be removing the oil filter and cutting it open ( tin snips, not hacksaw or grinder) and laying out the filter element, looking for bearing metal. If none, then not that?
Only cost you a new filter.

 

Pulled the filter and cut it open.  Oil is clean, filter element (Ryco Z30) is free from any metal, absolutely no sparkles in there at all - which ins a way is good and bad.  Engine has done around 4,000km since March when filter and oil last changed.  Will look at top end now.

 

Is manual trans, will pop inspection plate off and see if anything wibbly-wobbly in there as well today.

[Rockoz]

I can remember thinking my LC had terminal engine noises back in the day.

Turned out it was the throw out bearing that was making the noises.

Another nasty noise was when there was lack of lubricant on the distributor shaft.

 

Cheers

 

Rob

[lambretta]

After not finding any metal in oil or oil filter we started on the top end.

 

When I rebuilt this engine I didn't do anything with the hydraulic lifters, just refitted them, so I thought I should check those.  I removed all 12, dissembled, cleaned and refitted.  Nothing found broken.  I thought I would compare the current ones to a spare I bought new a few months ago and had in the spare parts box.  The metering valve in the ones fitted in the engine are solid spring steel with concentric circles embossed into them.  The meter valve in the spare has 4 holes drilled in it.  Which is correct?  See pic link - one of LHS is original, one of RHS is new spare.

 

https://photos.app.g...dz5xg3y87vpwK37

 

Any way, after refitting and getting everything back together we took it for a quick drive and...... it still makes the tapping noise, in fact now the taping noise doesn't go away once the engine warms up which is super annoying.

 

Next is removing fan belt and seeing if that makes a diff to the noise, hopefully its the alternator or water pump but I'm not confident.

[yel327]

Rob makes a point above, I’ve had a distributor make bad noises in the past too. Bit of lube under the points where it runs on the dizzy cam and it went away.

However by your descriptions I reckon it’s harmonic balancer or flywheel/clutch or a big end.

[LJ RB30]

Many years ago I had a noise after a high rev burnout that sounds like No2 bigend was gone.
Motor was a low k build. Took it out and stripped it replaced mains, bigends & rings even thought they looked.
Got it back together and fired it up and the noise was still there🤬🤬🤬🤦
The only thing I hadn’t checked was the Cam.
Turned out to have 0.011” end float. This was the noise!
Mismatched gears tried to drive the cam out of the block.

[lambretta]

With fan belt off the noise remains.

 

Have removed the distributor.  During rebuild I fully stripped the distributor, cleaned, lubed and rebuilt it so don't think lube is a problem,  See pics of the distributor drive gear.  Seems to have plenty of play between top of drive gear and bottom of disy housing which allows up and down motion of the distributor shaft and that by hand makes a knocking noise.  Notice also there is a slight chip to one of the teeth on the drive gear.  Could that be resulting in the distributor shaft going up and down and making a clunking noise?

 

If anyone has a distributor kicking around does yours allow up and down play like mine.  The gap measures 1.55mm.

 

See pics here ..... 

https://photos.app.g...kJ2VcSR7cyo3yZ9

https://photos.app.g...AEJhKSHW22gYK2A

 

As for cam - good tip.  Can't recall if I measured clearance there.  Can confirm this engine has aluminium gear for cam drive, not original linen reinforced phenolic resin one.

[LJ RB30]

Way to much endfloat on your dizzy.
0.1-0.2mm is what I try to shim them too.

[lambretta]

Way to much endfloat on your dizzy.
0.1-0.2mm is what I try to shim them too.

 

Nice, thank you. 

 

Do you use fibre and steel shims or just steel?  Do you pack inside dizy body (under the centrifugal advance mech) and between drive gear and dizy body equally or something else?

[LJ RB30]

There is usually a fiber between a metal shims under Advance mechanism and the gear

[hawk]

I had a very annoying knock in my motor, similar situation, thinking is was dead. pulled the box to check flywheel bolts and the spigot bush fell out.

I went through a couple with that set-up, assuming that the gearbox had a slight misalignment to the crank causing premature wear.

Cheap amd relatively easy one to check.

I have found loose flywheel bolts before too, even when torqued to the correct specs. I always use a mid strength loctite on them now.

[Bruiser]

“When I rebuilt this engine I didn't do anything with the hydraulic lifters, just refitted them, so I thought I should check those. “

“Any way, after refitting and getting everything back together we took it for a quick drive and...... it still makes the tapping noise, in fact now the taping noise doesn't go away once the engine warms up which is super annoying.”

Could be a cam/lifter wear issue
Do you remember if you just refitted them in the same holes on the same lobes?
Cams don’t like their worn in lifters being swapped around to different lobes very much
It is strange that things got worse after giving the lifters a pull apart and a clean out.

What did the bottom of the lifters look like?

[Rockoz]

Easy way to lube the distributor is to remove the rotor button and drop a few drops of oil on the felt pad in the middle of the shaft.

An old mechanic mate of mine used to use a large screwdriver to help isolate the location of any noises.

The old blue square shaft one from the Stanley sets was his favourite.

Place the metal end on the engine and the handle stuck onto your ear.

A stethoscope can be used with a tube instead of the standard end.

Helps isolate where the noise is actually coming from.

 

Cheers

 

Rob

[lambretta]

“When I rebuilt this engine I didn't do anything with the hydraulic lifters, just refitted them, so I thought I should check those. “

“Any way, after refitting and getting everything back together we took it for a quick drive and...... it still makes the tapping noise, in fact now the taping noise doesn't go away once the engine warms up which is super annoying.”

Could be a cam/lifter wear issue
Do you remember if you just refitted them in the same holes on the same lobes?
Cams don’t like their worn in lifters being swapped around to different lobes very much
It is strange that things got worse after giving the lifters a pull apart and a clean out.

What did the bottom of the lifters look like?

 

Yesterday when we refitted the lifters we put them back from where they came.  When I rebuilt the engine there was no order retained, just chucked them back in.

 

Bottom of lifters looked very good.  Shiney still with just a hint of wear.

[lambretta]

Well, today update is that, it seems to be fixed - or at east the very loud tick is no longer, seems to have been the distributor.

 

On Sunday I stripped the distributor again and basically gave it a birthday, lubricated everything again including the shims underneath the centrifugal advance mechanism (which looked to me to have started drying out grease) and shimmed out the excessive play between the drive gear and the underside of the dizy body (that sticks into the engine block). 

 

On Sunday evening test drive it seemed to me things were nice a quiet again but I wasn't convinced because it would have been a little warm still from previous test runs.  Monday AM I took it for a run and the ticking was hardly there when cold and disappeared very quickly there after.  Today my Son confirmed, it seems to be fine and have definitely removed the really loud tick that it once had.

[Rockoz]

Every month or so put a drop or two of engine oil on the felt pad under the rotor button.

 

I used to do it every oil change actually. But as a daily driver that was reasonably frequently.

 

Cheers

 

Rob

[LJ RB30]

Good to hear you solved the problem 👍
Got to love an easy fix😁

[lambretta]

Good to hear you solved the problem
Got to love an easy fix

 

See how it goes.  The shimming I have done would mean the dizy drive gear stays well engaged into the gear on the camshaft that it meshes with.