Engine fault second opinion

Got a Reliant 850cc in for some work...

The owner put 50% diesel in my mistake and then to compound it, allowed someone to alter the ignition timing etc "to get him home". He drove a number of miles on full choke as it was the only way it would run after this "modification".

I have emptied and cleaned out the tank, reset the points gap and timing, then reset the mixture. It was running reasonably well although every few minutes it would drop its idle speed and was obviously running on 3 cylinders. I put this down to a fouled plug and suggested he ran it for a while to see if it cleared, before fitting new ones.

Owner had it back and drove a few miles. He had to stop twice to fill it with water and he says it was blowing clouds of clear smoke from the exhaust.

Just put it on a compression test and have the following:

4) 250 dropping to 200 on subsequent tests, deposits on plug end. 3) 160 good plug appearance 2) 170 good plug appearance 1) 160 oily appearance of plug.

Now my experience of this engine is that it would be producing around 175 on a good engine. My suspicion is a failed head gasket, but I was taken aback by the high pressure being developed in 4.

I really really don't want to lift the head if I don't have to. It's a bitch to seperate the head from the block due to the studs. As yet, I have not done any coolant tests, but it didn't blow over during idle speed tests.

Reply to
Andy Luckman (AJL Electronics)
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Sounds like a head gasket or split head. Do a gas test over the water. The excess compression may be a massive build up of carbon in that cylinder.

Reply to
mrcheerful

If you put compressed air into each cylinder in turn with the valves shut, it gives you a pretty good idea of where the blow is and generally how good the rings are.

Reply to
mrcheerful

I have been round the block a few times with these engines....... An elderly customer in my village had one in his 3 wheeler. I did the head on it as it was blowing, just a little and using a little bit of water. I had the head skimmed etc etc , you dont need new bolts as it uses 3/8 UNF studs. one or two of the head bolts are difficult to torque down due to location. But in many respects a similar layout to an old BL "A" series engine.

6 months later the thing is using water again, reluctantly the took head off again , the head is flat and OK so???? Check projections on the liners..... one of them is lower than the block face!! So we ended up with engine out, crank and liners out, joint face of block skimmed to bring the liner projection back within limits ( lets say .003 to .005") proud of the block, bung it all back together and it has run perfectly ever since , but a LOT of work on a vehicle where access is a nightmare. It was never right when it was made, quality control slips when companies are in finacial difficulties. Final note . A main dealer told me that at one stage when they were going bust the Makers were buying engines and gear boxes from scrap yards, steam cleaning them and fitting them, to get cars out to dealers because their suppliers wouldnt send them vital engine and gearbox parts due to non payment.

So anything is possible. Steve the grease

Reply to
R L driver

Examination so far:

Dipstick tube full of mayonnaise. Same with oil filler cap. Oil spray everywhere. No water in the rad etc. My assumption is that cylinder 4 is part full of oil, which is why the pressure was so high.

So, I decided to lift the head. It's all dismantled, but the head is as stuck as they all are. That's a job to deal with today, but I have a dicky elbow that won't help!

Reply to
Andy Luckman (AJL Electronics)

The three near the plugs are the most interesting. I have a set of crowfoot spanners for those. They only need 15Lbs so not so bad.

I have seen a few examples. A customer bought a new car and had nothing but trouble. New axle, king pin and steering box etc required very soon and constant return to the dealers. When I had it in, it had done 24,000 and the engine was totally clapped. The gearbox showed all the symptoms of being

100K plus. My opinion was that they had taken a second hand rolling chassis and installed a new body.

It's such a shame, because the 850 engine is such a sweet and reliable little unit if setup right. One point for those working on these engines, it is important to retorque the head after a few miles. Otherwise the new gasket may well no live long.

Reply to
Andy Luckman (AJL Electronics)

No problem with the head or gasket. Number 3 piston was cracked in two places on the crown. Pic available should anyone be the faintest bit interested.

Reply to
Andy Luckman (AJL Electronics)

You must have missed something, where has all the water gone?

A split piston would give bad running, bad compression and loads of blowby, but wouldn't lose any water.

mrcheerful

Reply to
mrcheerful

That's the only mystery. Can't see any evidence of a gasket blow by. The head is flat, not checked the block surface yet.

All the above were present except the compression. Don't really understand that, but the cracked piston is there to see. Maybe the crack closes under compression? Dipstick and oil filler were full of mayonaise. Next step is to strip it more and have a good look. The head bolts were all over the place in terms of release torque, so maybe there was some leakage I couldn't see on the gasket.

Reply to
Andy Luckman (AJL Electronics)

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