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MG Midget and Sprite Technical - Oil Pan Find

Hi Everyone,
I have a '76 midget that had banging noise when the clutch was depressed some time ago. I have been refurbishing the engine bay and everything in it. Noticed some lateral play in the crankshaft. Dropped the oil pan to have a look and found what looks like a thrust washer. Could this be the source of the clutch problem. The engine has 71,000 on it, is it a good time to have it rebuilt ?


TMc Tim

yes
and yes

that cranck would like it thrust washer back
Onno Könemann

What Onno forgot to mention is that crank would NOT like THAT thrust washer back, rather have a new pair if you dont mind... With a full check and rebuild

:-)

Very well worn out, no sign of a bearing surface on it, so it is as well to open up and check all of the main bearings and crankpins too.

You may be lucky enough to just need to fit new bearings, but I have doubts from looking at the thrust washer

Bill

Has that one been pinned? - Photo looks like there is perhaps a pin at one end. Pinning is apparently quite common precaution to stop these dropping out when they get worn. You can get oversizes to compensate for wear.

And yes, it would affect your clutch. Missing thrusts allow the whole crank to move forward when you depress the clutch, so that some of the movement of the release mechanism is lost. The clutch would very likely not fully disengage.

Guy
Guy Weller

Was there any metal filings or swarf in the sump? If not and the engine was running fine before this, for the small expense of it I'd replace all the shell bearings and get some correctly sized thrust bearings and put it all back together. If its just the thrust bearing issue why rebuild the whole thing? Unless you're looking for an excuse to rebuild of course... ;o)

That is a known issue for the 1500 engine but they have to get pretty worn to actually drop out. For peace of mind I check mine regularly for lateral play and re-fit new thrust bearings as necessary. Something to bear in mind for the future Tim.
Bob T

Thanks Guys,
I don't know if it was pinned. I didn't see any filings in the pan,just a little sludge. It was running "ok" not perfect before. I have heard many things about the 1500 engine,might be a good idea to have it rebuilt.

Thanks agian,

Tim

TMc Tim

Tim

BobT knows the 1500 well & if he thinks a re-bearing job might be OK I would take his advice and see if you can get back in the saddle with just that.

Otherwise it can be very expensive to do a total rebuild
Bill

I'd also borrow a dial indicator to be sure you get the end float within spec. I'm guessing you will need oversized thrust washers.
Trevor Jessie

Hi Bob

K series thrust washers don't appear to wear and drop out! You should consider swapping to a K to eliminate this tedious feature... ;)

A
Anthony Cutler

As soon as i put a magnetic oil plug in the oilpan i got the same washer out as Tim.
Explains why why i had such a responsive clutch with the crank moving forwards and backwards. ;)

Went to a engine overhaull company and they suggested to put in a new washer but drill small holes in it so you can ceep it on its place with bras pins.
Arie de Best

the thrust washer issue is a common problem as I have come to find with various people I know that have a 1500

prop
Prop***The End in 2012

Pinning is fine if you have the engine apart. I used to replace these on my 1500, with a smear of bearing locktight on the backs.
End float on the 1500 crank is very easy to measure with ordinary feeler gauges.

Guy
Guy Weller

yep the best option is to buy an A-series midget :P

but bill is right it does not want that specific one back ;)
Onno Könemann

Tim, as long as the engine has good compression etc, there's no real need to rebuild it.

In this case, fitting new thrust washers is a darned good idea as in extreme cases the crank can move forward enough for the crank to hit the bearing castings and that will really do a lot of damage that may not even be repairable.

At the very least, I'd fit new thrust washers, refresh the main bearings and perhaps the connecting rod bearings. That should keep you running for a while longer.

Clive Reddin

The engine does have good compression. I agree it would be easier to only fix what is broken and the least costly. I think I will go that route. Thanks again everyone. I check this board often and always find good information you don't find in a repair manual.

Tim
TMc Tim

It's an age old problem with the Triumph 4-pot.

If the engine has been run with the thrusts dropped for any length of time then, chances are, there will be wear to the rear main bearing housing faces. If this is the case then the block is scrap (although you might get away with a replacement main cap and a line bore), so you will need to check this.

Pinning of the thrusts used to be quite a common mod (we did it on the race Spitfires 20 odd years ago), however it is not a panacea, since wear of the thrust face ultimately reveals the pin which then damages the rear main bearing journal side face(s) of the crank (not such a problem on a race car doing [say] 300 - 500 miles per season between rebuilds, but less than ideal on a road car clocking up mileage).
Deborah Evans

Fortunately though, you can replace the thrust bearings - as well as the mains and big-ends - without removing the engine, although it's a lot of fiddly grunt work. The crossmember makes it rather difficult to access the front ones.

But replacing the thrust bearings is definitely a good idea, and should provide some peace of mind. I really ought to do mine, for that matter. I've never had one drop out, but I've been in there and seen how they're fitted, and I understand why they should be carefully maintained.

On a related note, this strongly suggests that clutch use should be limited to gear-changes only, with no extended disengagement of the clutch at stoplights, etc., and definitely not at startup, before the oil pressure rises. I always start up in neutral with my foot OFF the clutch pedal.

Cheers,

-:G:-
Gryf Ketcherside

This brings back fond memories of my Triumph Stag!!! I had a judder from my clutch pedal that went away after a while so I thought no more about it! some time later when checking the oil I noticed shiney metal at the front of the crankshaft further investigation showed that the crank could be moved back and forth about 5 mm! sump off to find thrust washers in bottom of sump!! removed centre main bearing cap to find that crank had got very friendly with the bearing cap damaging both cap and crank!! very expensive!!replacement engine "common fault with Triumph engines" I was Told
Andy Douglas
AS Douglas

I chose to ignore the warnings about using a high lift cam and simplex chain and fitted a piper 276 to a 1098 A series. I ran well for about 10k miles or so then went down hill and on disassembling it I found these little crescent shaped pieces in the sump. Didn't twig for a few minutes but then inspection of the chain showed about 1/3 of the rollers on the chain had broken up and were in the sump. Next engine had duplex chain.
David Billington

I must admit that I have got into the habit of disengaging the clutch on start-up.

In cold weather when the battery is not at it's best and cranking slowly (and slower, and slower)I have found it helps to take some of the load off the starter.

The thicker gear oil in the 1500 box creates quite a bit of drag when cold, as well as having to crank the engine long enough to get fuel up to the float chambers.

Dave
Penwithian

>>> as well as having to crank the engine long enough to get fuel up to the float chambers. <<<

Not a bad thing, really, since you're also pumping oil around the engine before it fires.

-:G:-
Gryf Ketcherside


Ant, I would fit a K series but head gaskets are more expensive than thrust bearings...
;op
Bob T

This thread was discussed between 09/02/2009 and 13/02/2009

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