T140V no oil pressure/probably wrecked engine... - Triumph Forum: Triumph Rat Motorcycle Forums
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post #1 of 44 (permalink) Old 04-08-2019, 04:01 AM Thread Starter
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T140V no oil pressure/probably wrecked engine...

Hi All

Riding my 55,000 mile 1976 T140 yesterday and I became aware that the oil light was solidly on. On opening the oil filler cap to see if oil was returning lots of oil gushed out . I think I'm resigned to the fact that I will need to do a full bottom end strip but I am confused as to why there was so much oil returning- almost as if the scavenge side was working but supply side not. Is this possible? Could a blocked sludge tube cause it? I have ordered a new oil pump (although upon taking the old one off there is nothing obviously amiss ). Any ideas?
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post #2 of 44 (permalink) Old 04-08-2019, 05:09 AM
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Have a look at the flexible oil hoses, the interior disintegrates over time causing a restriction.
Another possibility is blocked engine oilways.
When did you last do an oil change?
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post #3 of 44 (permalink) Old 04-08-2019, 05:48 AM Thread Starter
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Thanks Caulky

I changed the oil two months ago (only about 50 miles done since) and there certainly seemed to be a good supply to the pump with oil coming out of the supply hole as I removed the pump.
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post #4 of 44 (permalink) Old 04-08-2019, 07:16 AM
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Hi Nclear,
I suspect that either the pressure relief valvehas stuck, (not very common) but you can check by just unscrewing it.

Or

The crankshaft oil seal in the timing case has disintegrated.(more commonplace).

Both scenarios will bypass a lot of oil into the sump, to be picked up by the return side of the pump.

You will get no return oil if the feed side of the pump has packed up and you will see no loss in oil pressure if the sludge trap is blocked.

As long as you have not ridden too far and fast with it, you might get away without damage, the sludge trap holds some oil and a surprising amount of flow/pressure is generated by centrifugal force.

If the bottom end has not been stripped before, 55,000 is probably a good mileage to have it apart though.

Good Luck
Peg
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Last edited by Rancidpegwoman; 04-08-2019 at 07:47 AM.
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post #5 of 44 (permalink) Old 04-08-2019, 07:31 AM Thread Starter
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Originally Posted by Rancidpegwoman View Post
Hi Nclear,
I suspect that either the pressure relief valvehas stuck, (not very common) but you can check by just unscrewing it.

Or

The crankshaft oil seal in the timing case has disintegrated.(more commonplace).

Both scenarios will bypass a lot of oil into the sump, to be picked up by the return side of the pump.

You will get no return oil if the feed side of the pump has packed up and you will see no loss in oil pressure if the sludge trap is blocked.

As long as you have not ridden too far and fast with it, you might get away without damage, the sludge trap holds some oil and a surprising amount of flow/pressure is generated by centrifugal force.

If the bottom end has not been stripped before 55,000 is probably a good mileage to have it apart though.

Good Luck
Peg
Thanks Peg

I've taken the timing cover off and the crankshaft oil seal seems OK (I will replace it though). Here's another thought (and maybe just clutching at straws) , I had just washed the bike then taken it out, I got caught in a local 1/2 marathon so spent about 15 mins at walking pace (i.e. getting hot). I suppose it is entirely possible that the oil overflowed due to slight overfilling + getting hot and the oil pressure light came on as water from the wash got into the boot.... it sounded a bit rattly (top end) rather than than knocky when I got back. Anyway plan is now to put new oil pump on (already ordered), check oil pressure switch is clean/dry as well as checking relief valve. Button it back up and see if the light goes out with kicking (it previously would extinguish on the first kick). Then make a decision

I bought the bike with 50k miles on it so don't know when the bottom end was last looked at , although evidence of gasket sealer suggests the two halves have been apart at least once. The top certainly has as it's on +60 pistons
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post #6 of 44 (permalink) Old 04-08-2019, 07:31 AM
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Fit your new pump that you probably didn’t need. Check the timing cover crankshaft oil seal hasn’t inverted or split or been fitted backwards. The writing on the seal should be visible where not covered by the circlip.

Clean the oil reservoir mesh, check that all hoses are clear, get the 20W/50 oil level right, take the spark plugs out (people have to be told that, apparently), turn the engine over with the rear wheel in top gear or with the kickstart (in neutral!) and make sure that the feed and return sides of the pump both pump oil.

A clear hose pushed onto the scavenge pipe in the crankcase bottom should suck oil out of a jar.

Remove the oil pressure relief valve and you should see small pulses of oil appear in the cavity after a few turns of the crankshaft.

If all that appears to work, fit an oil pressure gauge and start the engine. If the gauge reading does not rise to at least 40 psi at 3500rpm, stop. If the engine knocks, stop.

If the pressure drops (much) below minimum levels as the engine warms up, you’ve probably got big end bearing failure.

To be sanguine, a 55,000 mile engine probably merits a look in the sludge trap anyway.
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post #7 of 44 (permalink) Old 04-08-2019, 07:36 AM
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Last year a friend was riding my 79 T140 in a sporting manner... he pulls back in the driveway and says the oil pressure light is on..He didn't know how long but at least 5 minutes...A gauge confirmed no oil pressure...There was a slight return flow...I pulled and disassembled the pump, removed oil lines, and so on but found no fault.. Put it all back together and just like magic it had normal oil pressure...I rode the bike the rest of the summer and during the winter I tore down the engine...
The rod bearings looked just like this..



John Healy who has a long history building Triumphs told me no feed side pressure from the oil pump will cause severe bearing damage or a thrown rod quickly. But if the oil seal fails or something similar and the oil is still flowing, the engine will live for a while...
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Last edited by Truckedup; 04-08-2019 at 09:26 AM.
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post #8 of 44 (permalink) Old 04-08-2019, 09:13 AM
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Quote:
Originally Posted by Nclear View Post
Thanks Peg

I've taken the timing cover off and the crankshaft oil seal seems OK (I will replace it though). Here's another thought (and maybe just clutching at straws) , I had just washed the bike then taken it out, I got caught in a local 1/2 marathon so spent about 15 mins at walking pace (i.e. getting hot). I suppose it is entirely possible that the oil overflowed due to slight overfilling + getting hot and the oil pressure light came on as water from the wash got into the boot.... it sounded a bit rattly (top end) rather than than knocky when I got back. Anyway plan is now to put new oil pump on (already ordered), check oil pressure switch is clean/dry as well as checking relief valve. Button it back up and see if the light goes out with kicking (it previously would extinguish on the first kick). Then make a decision

I bought the bike with 50k miles on it so don't know when the bottom end was last looked at , although evidence of gasket sealer suggests the two halves have been apart at least once. The top certainly has as it's on +60 pistons
Hi Nclear,
Did the oil pressure lamp stay on when you revved the engine, or on the way home or when it cooled a little-how far was home.
It might be that the oil got so hot in the traffic jam that it was piss thin, Triumphs have a tendency to drop the oil pressure to pathetic levels on tickover under these circumstances.-enough to make the oil light come on at tickover.

It could also be pressure switch failure, giving a false impression of oil pressure failure, temporary fitment of a oil pressure gauge would certainly give you some reassurance of what is actually happening.

Your Triumph t140 pressure switch has 1/8th NPS (national pipe straight) thread 27 tpi.
If you are inclined to get an adaptor for an oil pressure gauge this is the size you need.
Try to get parallel thread (nps) and a sealing washer rather than taper (npt) thread as it is VERY easy to crack the case with taper thread.

Best regards
Peg.

Last edited by Rancidpegwoman; 04-08-2019 at 05:35 PM. Reason: Spelling mistake
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post #9 of 44 (permalink) Old 04-08-2019, 01:33 PM
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Last edited by Tritn Thrashr; 04-08-2019 at 06:03 PM.
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post #10 of 44 (permalink) Old 04-08-2019, 02:42 PM
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Drain the oil and pour it slowly into a white plastic container
Feel for particles/filter it and see if any metal is present

If you overfill the oil tank, more oil will rise up past the filller and into the tube under the tank. This swills rust into the oil so you'd be advised to clean this out.
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