Engine knocking

Post by **lowedb** » Tue Sep 09, 2003 1:06 pm

Be careful. Put Wynns in an engine of mine and it lasted approx 250 yds before dying terminally with a sheared oil pump driveshaft. I assume the pump tried to suck the lot in one go!!

Post by **Kevin** » Tue Sep 09, 2003 1:54 pm

I dont know how that would happen you just warm it up a little and pour it in the usual way, you could even have the engine running at the time, how bad was the engine before you put it in ?

Post by **lowedb** » Tue Sep 09, 2003 7:43 pm

low on oil pressure, and a bit leaky, but otherwise OK. Something definitely 'had' the oil pump / dizzy shaft though. It was in two pieces, but the dizzy was free. Never bothered stripping the engine to find out the detail.

Post by **Gareth** » Wed Sep 10, 2003 7:45 pm

I'd assume that that was just "one of those things"... Can't see how an oil additive could make the shaft shear off, really

If it was going to do anything, then excess wear could be a possibility. There again, who knows?

You could have been using the best quality oil in the world, and it would still have sheared off 10 miles down the road.

Post by **lowedb** » Wed Sep 10, 2003 8:12 pm

Ah. Maybe it wasn't Wynns, maybe STP? The one that thickens the oil, anyway.
It was certainly a lot thicker than engine oil. My guess was that being so much thicker, the pump tried to suck a whole gob of it at once, and had a bit of a moment when it suddenly had to work Very hard.

Post by **rayofleamington** » Wed Sep 10, 2003 10:56 pm

ugh - engine oil is meant to be runny not thick - if the stuff hadn't diluted properly then that could explain a sheared pump drive.

I wouldn't worry about the main bearings until you've done the easier jobs like the rocker shaft and big ends. These normally account for most of the pressure loss.

Post by **brixtonmorris** » Wed Oct 29, 2003 11:01 am

youve got worn main bearings on crank . this lowers oil pressure because it all runs out through gearbow bell housing. like putting your finger ont the bathroom tap. the tighter the seal your finger makes the more pressure builds up behind. a poorly applied finger ont he tap does not stop any water from comming out, just like the oil rushing past your main bearings tighter the main bearing the greater the oil pressure in the engine. may as well drive it untill you are ready for rebore and crank regrind, which will revitilise your engine.

Post by **rayofleamington** » Wed Oct 29, 2003 11:40 am

lots of places account for oil pressure loss on a worn engine.
I've seen one engine where it took >3 seconds for the oil pressure light to go out - that was due to a worn rocker shaft, and hence it is worth checking.
Similarly with the big ends - these can be done with removing the sump rather than taking the engine out. The big ends are more highly stressed than the mains - especially with low oil pressure so they will start to disintegrate leaving big chunks of the white metal missing, which is a leak path for the crank oil.

Doing those can add another 50 thousand miles life to a clapped out engine. It's often much cheaper and quicker to get hold of a good second hand engine than doing the rebuild - If you are very lucky you can get hold of the parts cheaply but that needs the gods to be smiling on you!
I did one where the 'new' parts had come from an unfinished project so the engine rebuild came to around £120 including £20 for my rebore.
(reground crank + bearings, + oversize pistons + a rebore + new cam followers, oil pump etc. comes to a lot of money and there's a big risk if you don't replace enough of the worn parts - if you can get a good engine for £50 then you're laughing)

Post by **Kevin** » Wed Oct 29, 2003 12:17 pm

If you take of the oil filter housing from the block when you have a doubtful engine there is generally signs of the white metal at this point just before it enters the housing , as I have observed to my cost.

Post by **57traveller** » Wed Oct 29, 2003 12:48 pm

Gained another 5psi in oil pressure once after renewing the rockers and shaft.
Don't know if anyone's tried it but an easy way of removing the sealing ring on the original type oil filter head is to slightlyand carefully bend the sharp end of a pin or sewing needle with pliers (about 30 deg.) then push the point onto the rubber ring, it usually then just hooks out. Sometimes a bit of a fiddle but it works, depends on how many times the ring has been re-used! A bit less brutal than using a hammer and screwdriver.

Post by **Kevin** » Wed Oct 29, 2003 3:02 pm

57 why not use the 90% pointed end of a scriber on the rubber ring I find it quick and easy.

Post by **57traveller** » Wed Oct 29, 2003 5:54 pm

Yes, good idea Kevin. I find that a pin or needle enters the rubber easier with a minimal risk of damaging anything. If the point refuses to penetrate the rubber then it's been in a long time and must be fairly hard, then resort to sterner methods!

Post by **brixtonmorris** » Wed Oct 29, 2003 7:03 pm

air line will get it out

Post by **winger300** » Wed Oct 29, 2003 11:26 pm

well my engine is still going. I have found that the knocking is only with high revs, i can get to about 50-60mph before it begins to knock by moving through the gears quickly.

Someone suggested this may actually be play in the gudgeon pin (small end??)

I have a spare engine which came with the car, so i'll fit that at some time. Only problem is that i don't actually know anyone who has seen this engine started, but they were assured it was in good condition. Whats the best way to check? or should i just risk it?

Post by **brixtonmorris** » Wed Oct 29, 2003 11:33 pm

hi winger if the engine is on the floor. a little test is to see how much the crank moves when you pull or push on it. it gives an indication of wear on the thrust bearings which stop the crank moving back and forwards. if it moves its worn.

Post by **brixtonmorris** » Wed Oct 29, 2003 11:35 pm

gey hold of the flywheel and pull. may be a small lever behind against the back plate

Post by **Willie** » Thu Oct 30, 2003 7:00 pm

I had worn small ends when I first bought my car. The
symptoms are that you get a metallic knock which is
present when both pulling and on the overrun....the only
way I could avoid it was by balancing the throttle when
up to speed so that I was neither pulling or slowing down,
a very hard condition to maintain for long.

Post by **rayofleamington** » Thu Oct 30, 2003 7:16 pm

to check out an engine (to save the wasted effort of fitting a dud)
some 'easy' checks:
1) Remove cylinder head to see if the bores are badly worn
2) take the sump off and look at the big end shells (and measure the crank thrust washers if you see any crank movement)

if these look good, then whilst you are at it you can dekoke and the head + grinding paste the valves, aslo de-slime the sump.

It will cost you some money for gaskets, but if the engine doesn't look great then don't buy the gaskets and don't fit the engine... and you'll have saved yourself a bit of heartache.
(and the engine is easier to fit without the head as it's lighter)

I'm sure some other people's opinions will differ - that's just what I'd do.

Post by **Kevin** » Fri Oct 31, 2003 5:49 am

Also if you have the room, space and spare bits you also try a compression test and if that seems ok try running it with an oil pressure guage to see what readings you get, someone on hear can probably tell what the ideal readings should be.