T140 conundrum

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Quick background:

1) Top end rebuild last season, including new barrels, head rebuild (new seats a'la Gord Bush), new KPMI guide blocks, and new cam followers (timed R radius)
2) Motor ran very nicely but quickly developed a low oil pressure problem once warmed
3) checked all the usual suspects, cleared oil lines, replaced oil pump (backup Morgo pump installed to be sure), new crank feed oil seal, new OPRV, scavenge pipe cleared in TS case, pressure checked to EX followers and crank

No joy, problem persisted. Discovered metal swarf on magnetic drain plugs, and since it only appears once warmed up I assumed a big end issue.

Fast forward:

1) cases split this weekend, took rods off expecting to discover a mess
2) crank journal look pristine, I mean no scoring, I set my MIC to 1.6235 and wouldn't clear the journal, set to 1.6240 and it's a tight sliding fit across the journals. I will plastiguage to confirm, but the journals are not the issue
3) just popped out sludge plug, the trap is clean, and I mean CLEAN, no gunge buildup (I've run with a spin on filter for 10 years now)

So, I'm at a loss right now.

Only things I can think of:

1) the tappets installed are actually not timed (though they measure up as such)
2) I somehow fubared installing the EX tappet block, though I don't see how, everything lined up (I'm dense, but not that dense)
3) cracked crank????
4) oil leak past sludge plug?
5) oil leak at tappet feed spigot in barrels (no oil leaked externally, but maybe dumping inside the case?)

Any tips welcomed, thanks for readings
 
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Did you look over your oil pump that carefully?

...oil hoses?
I did, even swapped with a known, good Morgo unit. Oil lined cleared, though if blockage was there I'd expect low pressure regardless of engine temp
 
Crank feed oil seal fitted backwards?
Won't explain the swarf though!
 
So you have a low reading AND an illuminated oil pressure warning light ?

What oil ?
Precisely. 20-50 Castrol, same as I've always run. Pressure has never been an issue on this bike, hot pressure at idle typically 20psi. Just plastiguaged big ends, .0010-.0015
 
All I can think of is some issue with the exhaust tappet oil feed. Ultimately you have after market barrels (I assume) and after market tappet blocks. Maybe something is amiss there and allowing too much oil flow and subsequent loss of pressure.

IFAIK it’s basically accepted that so long as hardened cams are used, the exhaust cam oil feed is not needed and many Triumph engine builders blank this off (a clutch roller is good for this).

S’all I can think of…
 
All I can think of is some issue with the exhaust tappet oil feed. Ultimately you have after market barrels (I assume) and after market tappet blocks. Maybe something is amiss there and allowing too much oil flow and subsequent loss of pressure.

IFAIK it’s basically accepted that so long as hardened cams are used, the exhaust cam oil feed is not needed and many Triumph engine builders blank this off (a clutch roller is good for this).

S’all I can think of…
Thanks Eddie, I had considered blocking off the feed with a bearing, but waffled after reading Mr Healy's warnings of doing so. I should probably look at the old barrels to see if the drilling was indeed blocked off, may explain a lot, and that ran for decades without a problem. Only reason I sourced new barrels was that I was at 60 over on the originals

Now that I've torn it down I'll replace all the bearings including in the tranny, and I may go ahead and throw a T120 exhaust cam in there, I've heard that will add some pepper
 
I had considered blocking off the feed with a bearing, but waffled after reading Mr Healy's warnings of doing so.

The factory dispensed with the pressure feed to the exhaust tappet block on later T140s.
T140 conundrum
 
Thanks Eddie, I had considered blocking off the feed with a bearing, but waffled after reading Mr Healy's warnings of doing so. I should probably look at the old barrels to see if the drilling was indeed blocked off, may explain a lot, and that ran for decades without a problem. Only reason I sourced new barrels was that I was at 60 over on the originals

Now that I've torn it down I'll replace all the bearings including in the tranny, and I may go ahead and throw a T120 exhaust cam in there, I've heard that will add some pepper
Yeah IIRC the T120 exhaust cam (irrespective of part number) is a 3134 profile and yes, that gives the T140 a boost.
 
T140 conundrum


THIS is a OIL PRESSURE RELEASE ( overload ) VALVE . ( Though its the superior Pre Unit One . ;) = the outer wotll fit ona Commando . Incidently . )

If the springs collpsed or oriental , it could well do that . Tho at idle ?

Also maybe check the face / at the pump .

Theres also the barrel / tappet feed .

T140 conundrum
 
I was about to ask about the OPRV but was beaten to the punch. Reason I mention it is because I had a similar event with my T150v last season. It was a fresh overhaul and previously never had a OP issue ever. Finally pulled the OPRV and I had forgotten it
had been apart and a new piston installed. But it sat 3 years with little use. After I cleaned it (no evidence of any dirt or whatever at all) reinstalled pressure was back to normal. The bore of the body was original and not in the best of shape but was unwilling to fit a new made one as they seem to be all SS. If I can find a original NOS I'd go for it.
 
I was about to ask about the OPRV but was beaten to the punch.
Quote from the first post:
3) checked all the usual suspects, cleared oil lines, replaced oil pump (backup Morgo pump installed to be sure), new crank feed oil seal, new OPRV, scavenge pipe cleared in TS case, pressure checked to EX followers and crank
 
Ah well I failed Reading Comprehension in sixth grade....looks like no change since then! :-(
 
Ok chaps, rebuild is coming along, bottom end buttoned up w/new connecting rods, 3 piece roller on timing side, new 3134 on the exhaust. Began dialing in the cams today and this is what I've got (based on reading through Mr Pete's threads on the BB boards)

Intake @ 101 LC
Exhaust @ 105 LC

Exhaust figure required moving to the B key slot on the wheel, standard A slot gives me closer to 101.

Thoughts?


T140 conundrum
 
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