Triumph Spitfire 1300 engine problems opinions please

[kartman24]

The engine in my car is getting very tired, it has compression between 85-95lbs on the 4 cylinders and it ticks over at 900rpm but is quite lumpy, if I remove the oil filler cap or the breather pipe from the rocker cover the revs jump up by 600rpm. Putting my finger over the breather pipe on the side that goes to the inlet manifold reveals that the pressure is sucking from the inlet manifold. The engine is using oil, 4.5 litres on the return trip from Le Mans Classic, my initial thought was rings but would that cause the sucking from the breather pipe connected to the inlet?
I have posted this on the Triumph forum but I am looking for speedy answers as am supposed to be doing an AutoSolo tomorrow in the car!............Martin

[catman]

I'm a bit rusty on older cars, but you would expect to have a vaccuum from the inlet manifold.

You seem to have excess pressure in your engine, which could be caused by worn rings allowing the compression to leak past them and pressurise the sump. This could also cause oil leaks.

I had similar problems on a Manta, which caused oil to be pumped out of the distributor. In my case though, it was caused by the breather inside the rocker cover being blocked and giving the gases nowhere to go.

Tim

[saaby93]

Don't the revs normally jump when you remove the oil filler cap - maybe not by that much?

[Dbest92]

On my mgb and midget 1500 when I had it (same engines as spitfire) the revs would drop when you take the cap off. Makes me wonder if the breather is blocked? This could explain the oil usage too

[Oldandslow]

I'd say Catman nailed it.

Inlet vacuum is perfectly normal.

Compression test is low so it's leaking somewhere, piston rings or valves. If excess pressure in the sump getting up to the head/filler cap then rings. The valves might be shot too but it'd be into the exhaust or inlet manifold anyway.

[Cerberus90]

You should be able to find out if the rings are worn by doing another compression test after putting a bit of oil (teaspoon) down the bore, if the compression comes up, then the rings are probably worn and not sealing well. If the compression doesn't change, then likely to be the valve stems/stem seals.

Do you get any smoke from the exhaust? If so, when?


+1 on the breather, you will have a vacuum, that's how the system works, sucks the gasses back into the engine, also how a brake servo works.


When was the engine last serviced?

[kartman24]

Thanks for the replies, the engine was serviced before the Le Mans trip, the pipe is not blocked, as I said there is terrific suction on it and if you reconnect it to the rocker cover the revs drop 600rpm...........Martin

[Dogwatch]

Air filter blocked - despite being serviced?

And despite the comment above BMC and Standard Triumph were rival companies so the engines are not the same.

[kev b]

Later Midgets used the Triumph engine.

[HumbleJim]

kartman24 said:

Thanks for the replies, the engine was serviced before the Le Mans trip, the pipe is not blocked, as I said there is terrific suction on it and if you reconnect it to the rocker cover the revs drop 600rpm...........Martin

Pipe off and the revs will incease because the inlet can draw more air, quite normal.

[catman]

kartman24 said:

Thanks for the replies, the engine was serviced before the Le Mans trip, the pipe is not blocked

The pipe may not be blocked, but as I mentioned, the breather may be.

On my Manta, it was a simple metal mesh arrangement inside the rocker cover that was causing the problem.

It was blocked solid, so no air could pass it, which caused the pressure build up within the engine.

If you take the breather pipe off at the manifold end, can you feel any pressure coming through it?

Tim

[caziques]

Engine number required, and which year and model of Spitfire? - lots of things happened between 1966 and 1974.

Compression that low could point to the wrong head gasket being fitted.

[kev b]

You really need a leak down test, shouldn't take more than 30 mins on a Spitfire,this will pinpoint where your problem lies.

Do all the obvious checks first though, breathers, oil grade not too thin?, did you do the compression check with the throttles open? then again with oil in the bores?

[tapkaJohnD]

The compression figure you quote may be low compared with others you have seen, but you cannot compare with those. A compression tester is not a precision instrument, it's uncalibrated, so that all you can compare with is the other bores on that engine, with that tester, at that time. You say they test at 85-95 (I think) - is that across the block? That is within the 10% variability allowed.

And the 'teaspoon of oil' test does not reveal leaky rings, because rings always leak, a bit, and the oil witl always improve the seal! The test discriminates leaky rings from a leaky valve. If a valve seat or head is damaged, so that there is no seal there, the oil will have no effect.

Try it. If all your compressions are the same (+/-10%) I will be surprised if you will find a leaky valve, as that will cause that individual cylinder to be low.

A blown head gasket will show up as two adjacent cylinders beign low.

When you remove the oil filler cap, is there a mighty wind coming out? Or just a gentle breeze? The second case is normal, you probably don't have leaky rings. And another test is to idle for a few minutes and then accelerate. At idle the chamber pressures are minimal, and oil can be sucked in past leaky rings, to be burnt and blown out in plume of blue smoke as you accelerate. Excess oil consumption can have many causes, but exclude the rings first.

And, with respect to your advisers above, all of whom know whereof they speak, but some from general knowledge, try one of the dedicated Triumph sites for specialised knowledge:
Sideways Technologies; general but Triumph based: http://sideways-technologies.co.uk/forums/
Club Triumph: http://club.triumph.org.uk/cgi-bin/forum10/Blah.pl...

JOhn

Edited by tapkaJohnD on Sunday 20th July 10:33

Edited by tapkaJohnD on Sunday 20th July 10:43

[Slidingpillar]

Another small point is the figures for compression are arrived at by cranking the engine over with the throttle fully open. If the throttle is at the idle setting - a much lower compression figure is arrived at.

I'm hopefully teaching granny to suck eggs, but the mistake of compression testing on a closed throttle is fairly common.

[tapkaJohnD]

kartmann!
You personal details show an MG Midget! Quite correct - later models used the same engine as the Spitfire, but not AFAIK, the early 1300. They shared the 1500.
John

[kev b]

I don't know if this will work on the antiquated Triumph engine but there is the "rubber glove test" which is very useful for checking BMW breather systems.

A latex glove is placed over the oil filler opening, with the engine running, if it inflates like a balloon you have excessive blow-by or a blocked breather, if it just sits there everything is OK, if it gets sucked into the engine you have a faulty oil separator and massive oil consumption.

Perhaps someone could try this on their healthy classic and see if it is valid.

[garagewidow]

from what the OP describes it seems to be connected up wrong.

this is a 'positive vacuum' type of breather and sounds like it is connected to the inlet manifold tapping that may be used for a servo(high vacuum requirement)and normally blanked off.

if you have su's generally they have a take off just behind where the throttle plate sits and is a small drilling,typically 3/16 - 1/4 "with a brass tube sticking out which is fed from the valve cover to a tee piece then to each carb.the vacuum here is less so will not cause excess pressure drop and hence reduce oil consumption.

if your revs rise when you remove either the pipe or oil filler cap I would suspect a over rich mixture(cause of lumpy running perhaps?)the sudden increase of air should kill the engine almost straight away.

you could put a restrictor in the pipe.try a washer with a 1/4" hole or smaller to reduce volume or connect as above.

the glove idea above will not give a true indication of blowby volume as the engine is not under load when revving freely,needs to be on a dyno to see the real amount of gasses escaping.

oh,and the triumph 1500 was in the rubber bumper midgets.

[catman]

Any update OP?