Bottom end noises

[polo2k]

Ooh Err!!!

-but seriously!-

noises from the bottom end (knocking) if they are the mains, or indeed any of the bearings on the crank, would the noise be prevalent when the engine is under load (20mph in 4th at a wide throttle opening).

The reason I ask is im having some nasty noises in mona but the engine pulls like a train (a small one), starts beautifully. I dont remember too much about the condition of the bottom end as its 9 years since I last saw it. The noises are NOT there under load at low revs, only when going from power to coast. the sounds seem to be engine related but I was wandering if It could be the exaust (stainless 2 piece) as it is quite close to the shell in places.

What are your thoughts?

[MoggyTech]

First thing to check, oil pressure. Worn big ends give a slight drop in pressure, and usually make less noise when under load. Main end failure usually gives quite severe vibrations as well as large drop in oil pressure, and the noise/vibration is usually worse under load.

Look for 60PSI hot above 30 MPH in top gear, and 40 PSI hot at idle.

Could also be prop shaft UJ's especially the front one, if the noise seems to come from the front.

Another clue to Main End Bearing failure, is excessive oil loss into the clutch bellhousing. So much oil escapes from the shells, the scroll seal on the crank can't wind it all back into the sump.

Big ends can be done with the engine in the car, engine out for Main End Bearings, and of course any crank regrinding.

[polo2k]

dont have a pressure gauge but I ended up raising the tickover manually to approx 2k (i guess) to get the oil pressure light to go out!

[alex_holden]

dont have a pressure gauge but I ended up raising the tickover manually to approx 2k (i guess) to get the oil pressure light to go out!

That doesn't sound healthy.

[MoggyTech]

Oil Pressure light only works below 4 PSI, and if it stays on with engine running, the damage is done. Time for an engine rebuild I think, or drop a recon in there.

[Packedup]

That doesn't sound healthy.

That's a far more polite way of putting it than what went through my head when reading the post!

Indeed - Knocking and poor oil pressure - I'd suspect bearings. I've lost one on my 1275 Metro, and after filling it with oil thickening gloop it doesn't knock too much, but does vibrate and there is a lack of power. Luckily the gloop and only doing low speed runs has stopped the warning light coming on again, but it's only going to get worse not better (I need to finish the pickup before I can fix the Metro, and I need to use the Metro to get the 20 miles each way to work on the pickup...).

The good news is the big ends aren't too bad to get to on a Minor, no gearbox in the way which is why I've not done my Metro.

[polo2k]

well ill probably have a ring around the local suppliers and which ever one has got a micrometer will probably have me at their counter an hour later with my spare crank. Im just gunna bite the bullet, rip out the mains and the big ends, pull the engine while the missis is getting ready to out, do the shells while shes in town and hopefully have it all done sunday eve.
somewhere in there ive got to fit in a BBQ with the north wilts mmoc branch, Ill drive here there and back but its only about 3 miles round trip. The banging/nocking is barely audible when the oil is still cool

[MoggyTech]

Do the engine a huge favour and fit a new oil pump while it's all in bits. Cost v Hassle, it's not worth the risk of using the old pump.

[bmcecosse]

New oil pump is essential - and have a look at the relief valve too - there may be 'bits' jammed in it. An oil pressure gauge is almost essential. And when the engine is out anyway - chance to sort out the timing chain - and check the clutch carefully.

[grumpygrandad]

i have just done the bottom end on my morris oil pump only £15 . about £120 including 2 engine mounts this included timing chain conversion to duplex ,very easy conversion just countersinc .twu holes, grandad

[XDB]

I recently pulled a mates engine out of his Minor to renew the clutch. I persuaded him to remove the sump just to check the bearings. The big ends were fine, but the centre main bearing was down to the copper backing. So it was out with the crank, all the mains were down to the copper but the big ends were ok. The crank was cleaned and measured and was within tolerance. Whilst the engine was in pieces I renewed all the core plugs, fitted a new oil pump and relief valve, converted it to dual timing chain. It was rebored and new pistons fitted, new shell bearings and lock tab kit including all the gaskets went in. The parts were just over £300 with the new borg and beck clutch. and the rebore was £75 not a bad job for less than £400. By the way the parts replaced included new engine and gearbox mounts, gearbox seal and rubber bungs x3 and new stabiliser bushes.

The engine ran ok before the rebuild, but runs much better now, by the way my labour, nowt.

[polo2k]

I pulled the engine (with the help of Rob) and ripped the bottom end out. The mains were well into the copper. I had a spare crank so fitted that. The shells that came off that crank (very good condition) were marked 20thou, so I went and got a full set in 20 thou. upon fitting it turned out that only the mains are 20 thou and the bigends are standard size so hopefully I should be able to get some standard size shells today

[Kevin]

Dont forget the thrust washers as well especially as they are only around a tenner.

[bmcecosse]

Thrusts rarely need replacing - just swop them over side to side. But DO get a new oil pump!!