Camera inside the engine

[carmadmike]

Hi

I have just put a camera inside my 2.5 vitesse engine and have found that some of the pistons have quite a bit more Carbon than others. No1 has very little and you can see the 20 thou oversize measurement on the piston. No 2 has a lot of carbon and looks thick and wet. 3 and 5 have less and 4 and 6 are quite thick like no 2. It also has what sounds like a misfire which is worse when cold and still there when warmed up but not as noticeable. Its running on dolomite sprint su carbs and has the inlet manifold ground away on port's 3 and 5. Could the manifold be the problem. Any thoughts appreciated.

Mike

[Clive]

so no1 is ok or lean, 3+5 a bit carboned up 2,4,6 worse.

No idea on teh manifold, and as it is not unique to one carb I doubt mixture (although front may be a tad weaker, but nothing worrying)

No water, even a tiny bit, getting into no1 and keeping it clean?

When did teh car last have a good long fast run? That may help, as might plugs. 

But best not to get too paranoid, you may be looking for a problem that in te real world does not exist (except teh misfire when cold, but that may even be damp leads)

[glang]

Think a compression check would useful or even better leak down test....

[carmadmike]

Compression test cold 

Dry

no 1/ 157psi ,no2/ 190psi, no3/ 167psi, no4/ 177psi , no5/ 190psi, no6/ 193psi.

wet 

no1/ 162psi, no2/ 230psi, no3 /200psi, no4/ 185psi, no5 /200psi, no6/210psi

Mike 

 

 

[Clive]

So the lowest compression is no1, the clean one. 

However, I should ask if teh tests were done with wide open throttle, as there is little correlation between wet and dry readings. ie no1 and 4 increase under 10psi, 5 by 10psi 6 by 17psi and 2&3 by about 40psi.

I think there is essentially some wear on the engine, best bet is to sort the misfire and carry on as you are. Unless yoiu fancy a job over the christmas period, and need to create a pressie list.

[RRR]

To me the evidence points to a poorly a valve seat on No 1 cylinder. The washing off of the carbon from the piston indicates that fuel is bypassing the valve. This is supported by the low compression reading on No1 cylinder.

Looks like time for a de-coke, and re-grind the valves.

Hours of fun.

[carmadmike]

Thanks for the replys, test was done with open throttle. Think I'm going to have to lift the head and sort out no1 valves and check the others. Is there a way of checking for engine bore wear or broken rings while the head is off without dismantling to the pistons or are those compression figures ok.

Mike 

[Clive]

I would look at doing a leakdown test before taking the head off. That will tell you if it is rings, inlet or exhaust valves. 

If you do take the head off, you can pour a set amount of paraffin or similar in each bore, time how long it takes to drain. Compare across cylinders. 

[Nick Jones]

Does it use much oil or any water?

Suspect you are getting a bit of water in no.1. Possibly head gasket but also possible it’s getting in through the water rail in the inlet manifold, which occasionally go porous at the ends where the pipe stubs are cast in. Had this with my Vitesse years ago though at the other end on cylinder 6. Found largely by chance though I had been aware of a slight unexplained coolant lost for a good while and also wondered why that plug always looked a bit different.

[carmadmike]

No it doesn't loose any water or use any oil. And I haven't noticed any blue some from the exhaust. How can I check if the manifold has gone porous do you take it off block up the openings and fill with water to see if it leaks or goes down. Also how do you do a leak down test

Mike 

 

[carmadmike]

Does anybody know what the spark plug thread is. I've been looking at the leak down testers and can only find m12 and m14 adapters and not sure if they will fit.

Mike 

[RobPearce]

M14

There's really only those two threads used for spark plugs, with the smaller being a motorbike or small 16V fitment. A few others have been used but not on anything as mundane as a Triumph.

[carmadmike]

Thanks Rob I now have one on its way.

[carmadmike]

Just a quick update and sorry for taking so long.

Did the leak down test and everything came up ok except I noticed that the valve clearances were a bit tight. So readjust the valves and it now seems ok.

Hope this may help someone in the future.

Mike

[glang]

I think I can still see some cross hatching marks in the first bore photo from honing so that might indicate it recently had some work? Id keep an eye on the valve clearance as if its exhaust valves that go tight again it might be down to seat recession where hardened ones havent been installed...