Britbike forum Forums British Motorcycle specific Brands Triumph bulletin board ‘79 T140E oil light flicker

Good evening
This is a new one to me .
A new Brit bike owner and friend did his first oil change on his new to him ‘79 T140E with low miles on it . (Indicated 7500)
He used Spectro mineral Heavy Duty 20w50 which is what I use in my ‘76 T140V .
Cleaned the frame screen and the engine screen .
On third start up with engine cold, the oil light flickers below 1500rpm.
Over 1500 the oil light goes out .
At idle, the oil light is solid on.
Before the oil change the oil light behaved normally .
Key on, light on. Engine start , light off .


Thanks in advance .
Curious in Clovis

Hi, AL, Seems there has been a rash of low oil, pressure recently. Why all of a sudden is a mystery.

Do you have an oil pressure gauge? The thread is in timing cover is an odd ball thread, not at all common in automotive use. 1/8-27 NPS National Pipe Straight. REPEAT STRAGHT, NOT TAPERED.

All but impossible to find a correct fitting. However.... you can most carefully use a 1/8-27 NPT fitting SCREWED IN HAND TIGHT AS YOU CAN. If you put a wrench on it, the timing will crack very easily. The Harbor Freight oil pressure test kit is what I use. The tapered screwed in hand tight. Yes it will drip some, but no matter. It only takes several seconds to test the pressure. If you know if machinist, they can make you a proper straight thread adaptor.

In the mean time if you don't have gauge, to start with, you could remove pressure relief valve & see if it's stuck open. The exit holes in side of valve should be fully covered by piston. Piston should slide freely. Spring is often shorter than spec in book, but if not obviously broken or damaged, a little short doesn't make any difference at 1500 rpm or below.

Switch could be bad, but without a gauge it's hard to tell. So, end of day without knowing actual pressure it's guess work.

Be advised the pressure will often test ok cold but be can quite low hot oil. Can take about 20-30 miles to really heat the oil.

If pressure is actually low at lower rpm, if PRV is ok, it's time to pull timing cover & inspect crank seal & pump.
Don

For the front oil galley tap on myT150V, I made an adapter to 1/8" compression fitting on my small lathe. I run 1/8" SS (doesn't work harden like copper) tube up to the headstock, then union to 1/8" (nylon?) tube to the gauge on the handlebars. Switch is still mounted and functional to give the "idiot light" (necessary for me).

Thank you . I think The guy is ok with buying the aftermarket oil guage as a testing piece . Just saw the HF oil pressure guage kit is only $30 so I think the way to go. Great suggestion .
Ok, here we go .
Have a good weekend .

It is odd that it was ok before the oil change and then bad after. What can you do in an oil change that could change the oil pressure when running?

Dave

My point exactly .
If it makes any difference . The old oil was old and thick . Perhaps a 50w or 60w but still a head scratcher .

Sounds very much like a dodgy salesman has gouped up the oil with something thick to make a sale.

Hope thats not the case but its looking that way to me.

“It is odd that it was ok before the oil change and then bad after. What can you do in an oil change that could change the oil pressure when running?”

Assuming that was the only thing you did at that time, there aren’t many things that could change.

Contrary to some comments, oil doesn’t get thicker (more viscous) with use. The longer chain hydrocarbon molecules gradually get broken, resulting in a more “watery” fluid.

The crank seal is exposed to the highest stress (pressure) at cold start. That is the most likely time it will fail (either by splitting or inverting).

The old seal may have been at the end of its service life, but still survived with the old, thinner oil.
When you put in new, thicker oil, the failure probably happened at startup.

That’s the first thing to replace. It’s cheap.
If that doesn’t work, you’ll have to inspect the pump (in case you introduced a bit of muck).
Both of these might as well be done at the same time, when the timing cover is off.

I’d check the oil pump, clean it, reseat the balls.

There may be dirt under a ball valve.

And inspect the crank nose oil seal.

He bought it from an old friend and the bike had been in the family many years just sitting .
Been trying to buy it for a long time .

I often see “reseat the balls” but does it actually work?

With the very early bronze pumps, probably so, but with the usual cast iron? Not so sure.
It’s a bit like hammering a valve into its seat, rather than grinding it.

If you do bash the ball into the seat, at least use a new ball afterwards!

I’m doubtful that any improvement done by doing this is due to reforming the seat, it probably just smashes through a bit of stubbornly stuck muck.

Why would the seat surface degrade in the first place?

I did it on my 650's brass pump because it said so in the Triumph manual. It also says not to attempt it on a cast iron pump or it will be ruined.

My first bike was a Triumph Blazer 250. Because I was daft I bought it even though the person selling it said that it had to use 10w30 instead of 20w50 or the oil light would stay on. Without thinking about it too much I ran it on 10w30 and the light stayed out. This seems contrary to the more normal oil too thin means light on. Maybe it was the rotary pump.

Dave

My second bike, briefly, was a Starfire, pretty much the same. I don't think it makes any difference to the laws of viscosoity. I think you or the seller got it mixed up. Doesn't matter what type of pump it is.
I've never seen a brass pump on a B-range twin, what year was it?

Hi All, The timing cover must be removed anyway to access oil pump, so obviously you'll look at crank seal.

The very first thing to do with pump after removal is bench test it. Very simple. If pump passes bench test, the balls are sealing. At least at this moment.

All the 650,750 twins unit construction have "brass" pump. At least I've not seen an iron one.

I've tried to reseat balls on 2 pumps that had leaking by balls. Cleaning first made no change. I ended up beating the one pump silly. Still didn't change sealing. On my pump I replaced 3k miles ago the return ball was leaking down slowly. Knowing better I didn't hit ball. I will try to lap ball seat in with very fine lapping compound. Then replace ball & recheck for leaking. The return side of pump ball seat tends to wear faster. I feel due to particulates in oil. In my case the timing side metric ball type main bearing failed. Sent metal flakes into motor sump & through return ball of pump. I was using in frame filter with large magnet. The seemed to contain all chips. I flushed frame, steel tubes, replaced rubber hoses. Replaced ball with roller bearing on timing side. So far so good, but only 3k miles so far.

End of day, if pump passes test, the problem is not the pump. Would I clean it anyway, of course. But DO NOT reseat balls like manual states. A pass is zero leak down in port. PM me your email if you want to see videos of good pump & leaky pump ball.

Regarding oil pumps, the oval port pump introduced in the model year 1970 has substantially larger volume per stroke. I installed Morgo pump in place of oval port on my '73 Tiger. The Morgo is round port with larger piston diameter than Triumph pump, thus more volume than Triumph round port. However the Triumph oval port pump has a fair amount more volume than the Morgo. This can be visibly seen in return pipe & with oil pressure gauge with hot oil after 50 miles riding at idle. So should you need new pump I'd recommend LF Harris oval port pump. Not Emgo! Make sure you actually use correct T140 gasket on pump. It's different.

The thought of new cold oil being thicker could split aged crank seal in timing cover is valid. This is long thread, but actually shows photo of aged crank seal fractured resulting in low oil pressure. A long & still ongoing thread. Worth the time if you are having problems.


https://www.triumphrat.net/threads/78-t140e-oil-pump-replacement.995462/

Don

“All the 650,750 twins unit construction have "brass" pump. At least I've not seen an iron one.”

What!? What on earth do you mean Don? All the pumps on Triumphs are made of cast iron/steel.
Allegedly there are some early ones made from bronze, but I’ve never seen one myself.

Koan
All the unit triumphs had bronze bodied pumps.
I don't think they ever made an iron one for the unit motors.

I've never seen an iron pump on a Triumph twin. I can say for sure that all unit twins had brass pumps (I think they are brass, not bronze which is far more expensive)

I crawl into a pre-unit corner of ignorance!

LOL, Don't loose sleep over it.......

My old pre-unit pumps were iron which is a better material but all the unit
ones i've had have been brass or a brass alloy, i assume a type of leaded bronze.
I've never had one professionally analysed. I'm not that anal.

Harbor Freight guage set purchased .
Cold engine, less than 5psi at idle . 15psi at 2500rpm.
He removed the oil pressure relief valve . All clean and clear .
So next step has to be replace the end seal and while there remove the pump and check for debris I’m assuming .

Cold oil pressure is normally plenty high enough to turn off the idiot light, even with lower viscosity oil. If all this is happening with cold oil, here's another possible explanation for why the sudden change.

When the screen was cleaned, debris could have inadvertently gotten into the feed pipe and was then drawn into the pump and finally prevented the check ball from seating after running a short time. All this to say that the pump will need checking (seal too) but it also would be a good idea to make sure there isn't any debris in the feed line.

I must have at least half a dozen pre-unit oil pumps, all brass. I tend to fit Morgo's with my big bore conversions. I haven't actually tried it, but I suspect that you could lap an oil pump seat with a ball glued to a stick if push came to shove.

Tapping the balls onto their brass seat, as described in the manual, has always worked for me.

Brass and bronze are often confused with each other, and are more often than not referred to as "copper alloys" these days. However, as brass is typically more malleable than bronze, it's often used for instruments and vases and such, while bronze is used when resistance to wear and corrosion is needed. I'm pretty sure that Triumph oil pumps are made from bronze. Personally, I've never seen an iron oil pump in a Triumph engine,, and I have actually seen a few.

SR