45 replies to this topic

[Hippy23]

Hi I have a loud knocking/ticking noise coming from 998 mini engine. It was just rebuilt 3 years ago and has only just made it in the car but I’m beginning to suspect that it’s not been rebuilt very well. A few days ago I was getting this noise every time I let off the throttle or just touched the throttle slightly while driving. There is no noise while the car idles unless its hot.

I changed the oil yesterday and put fresh 20/50 in and run the car again. It was fine when the car was cold but once it heated up to temp the noise appeared again. Now every time you put the engine under load while driving you here this knocking noise. I checked all the pushrods to ensure they are straight with no damage and they are fine. I checked all the valve clearances again and they are all set to 0.012. When I drained the old oil there was no visible metal filings and the oil plug did have some crap stuck to the magnet but nothing too bad.

I have also noticed yesterday that when you depress the clutch the revs drop down on idle. They drop nearly to the point where the engine will cut out. I’m not sure if this is related or not but again it only does this when the engine is hot. The engine is fitted with the old style diaphragm clutch setup. Again it’s a brand new clutch. I have checked the oil pressure and it seems all good. I don’t have a gauge fitted but I did undo the nut from the oil filter to the block and there seem to be good pressure there.

 

I recorded a short video yesterday of me going from 1^st to 2^nd to 3^rd so you can hear the noise from the engine. While in 3^rd I just lightly tap the throttle on an off so you can hear the knocking noise.

 

https://photos.app.g...KSfH9fFnQzK3217

 

 

If anyone has any idea let me know but I think the engine is going to come out this week as I suspect either it’s a bottom end fault or possibly cam followers damaged.

 

Cheers,

 

 

 

 

 

 

 

 

 

[nicklouse]

I am not able to access the video but will do later but some questions.

 

who did the rebuild?

 

was it bought from Ebay/gumtree?

[Hippy23]

The engine was rebuilt by a friend who has been a mechanic for years. I do trust he did a good job but i think he may have missed somthing. I have all the invoices for all the new parts that went in too, like bottom end shells and gaskets etc. 

[GraemeC]

Has it been rebuilt completely as standard or some uprated parts such as different rockers?

Sounds a little like the rockers hitting the rocker cover, but I'll admit I was listening to it whilst walking the dog so there was a lt of background noise my end!

[Hippy23]

Its all standard internals. Nothing is uprated in the engine.

I did look at the underside of the rocker cover when i had it off but i did not see any markings.

 

I think its more down near the bottom end, camshaft or clutch the noise is coming from but its hard to tell.

[Retroman]

Hate to say it but it's goosed

 

Don't run it any more you are only adding to the cost, and it might let go all together

 

That sounds to me like a big end or main bearing knock

 

The fact that pressing the clutch changes it means the crank end float is excessive and its stressing the bottom end too.

 

It needs to come out and be torn down to find and possibly cure the issue.

 

If you need it doing PM me

[Hippy23]

I suspected that bottom end is the issue. Im going to get this engine out this week and get it ripped apart to see what the issue is. I have another 998 engine sat in the garage but its sized solid so thats not much use either.

 

I will let you know what i find once i get it torn apart.

 

cheers,

Edited by Hippy23, 29 October 2018 - 11:18 AM.

[Retroman]

Ok It will be interesting to know

 

See if you can measure the end float on the crank before its all in bits

 

Keep us posted

 

Best of luck

[mab01uk]

If you do run the engine again fit a temporary oil pressure gauge to see what it reads when oil is hot and cold.......any Mini engine should really have an oil pressure gauge fitted in my opinion, so it maybe worth fitting one anyway for the future.

Edited by mab01uk, 29 October 2018 - 12:34 PM.

[Magneto]

I agree with Retroman, it sure sounds like bottom end. Only other thing I've heard like that was a stuck piston pin, meaning the piston could not rotate on the pin and was hitting the side of the bore....but this sounds like bottom end to me too.

[nicklouse]

I am not able to access the video but will do later but some questions.

 

 

oh that be fubar

 

PS dont drive run it any more or you may just find a conrod saying hello through the block.

Edited by nicklouse, 30 October 2018 - 12:06 AM.

[Hippy23]

Well I got the engine out, head off and got the clutch stripped off last night in 2.5hrs which I think is pretty good going.

I got the cylinder head off and it all looked good but as I took the starter motor out I was met with some oil, then as the clutch cover was removed I found that the release bearing had broken in 2, not a good sign. As I removed the flywheel and clutch I noticed the clutch plate was soaked in oil also………... and then I found this.

 

https://photos.app.g...Wag1P29RkSRRZX9

 

Excuse the language..

 

I think is safe to say that I won’t need to get my stand and dial gauge out to tell me I have a bit of play in the crank L . After I found this I said enough was enough for tonight and when and poured myself a large drink as if it can be rebuilt it’s going to be dam expensive by the looks of things.

 

Hopefully I have enough enthusiasm tomorrow night to get the rest of the block stripped and I can inspect what’s left of the bearing shells and the crank.

 

Cheers,

[GraemeC]

Wow - I don’t think I’ve ever seen that much movement!
I wonder if there are any bearing shells in there? Or the caps haven’t been tightened.

Chances are you’ll be after a new crank and obviously main bearings.
If you need a 998 crank send me a pm - I have one on a shelf and I’ll never use it, you can have it cheap.

[imack]

Crank broken?
Friend of mine broke a 1098 crank just behind the transfer case.

[Hippy23]

I don't think the crank is broken as the engine was still running before i took the motor out but i will find out tonight what the problem is.

 

Cheers Graeme. I have a sized 998 that has been sat outside for about 10 years with no plugs in it so i may try to salvage bits from that or maybe rebuild that instead of this one.

 

I can't believe this was still running. Hardy wee motors these things