fleehillfarm

Thanks for the replies from Mick Jones and Muddy42. The route that I have taken is that I have removed the cylinder head and replaced the head gasket of the smoking right hand cylinder and it made no difference at all. To remove the crankcase I would have to take out the engine which I am reluctant to do, especially as the right hand cylinder which seems top be the one that all the smoke is coming from is still now ( I tested it again this morning) showing a 100psi compression. The left hand cylinder which I haven't replaced the head gasket is 75psi. Surely a compression of 100psi must rule out piston ring bypass. I'm wondering whether there is anything I could have done wrong when I cleaned the carbs that could cause such serious smoking. If I remove the cylinder head again I'll try the oil test as suggested.

After watching a couple of videos on Youtube I see that I was being incredibly stupid. Of course after removing the cylinder head on a Briggs and Stratton you are down to the main body of the engine and crankcase. I was thinking of the bike engines that I worked on when I was a kid. Taking apart Triumph 500cc Speedtwin and T100 engines where you took off the cylinder head and then the barrel and the crankcase was a separate entity so you could access the piston rings. Anyway so it has to be engine out or the scrapyard.

Thanks I will certainly give that a try. Maybe with WD40?

Thanks I will certainly give that a try. Maybe with WD40?

I finished the work on the head gasket yesterday. I was pleased that it started immediately. Only trouble is it's exactly the same. Pouring smoke from the same cylinder. What a disappointment. I suppose the only remaining possibility has to be the piston rings. Does anyone know if I remove the head again, will I be able to access the rings by removing the next section of the cylinder barrel without stripping down the engine completely to remove the big ends and release the piston completely. I think that would be a step too far for me. Changing the subject for a moment. When I ordered the gaskets I needed online I chose a company at random on the internet called Briggs Bits. I put in the order at 2.20 pm and I received a dispatch notice at 2.45 pm. They were sent Royal Mail 48hour tracked post. Received within two days. Super efficient service so I would thoroughly recommend them if you need any parts. I don't think I have ever had a turn around service of twenty minutes before. Getting back to the subject of old smoky any advice would be much appreciated.

Hi everyone - I took the head gasket off this morning and it was pretty much knackered. I dont know whether it was rough enough to have caused all the smoke. I'll find out when I put it back together. Also the gasket on top of the head where the inlet manifold is attached to the head was completely destroyed and in two pieces. That may be even more relevant. I don't really know. Anyway I'll update as soon as its back together which may be some time as I have to source the new gaskets online.

I think you are right it's looking more like a blown head gasket on the right cylinder. It would appear from doing a bit of research online that you can still return a good com pression even with a blown gasket depending on where the gasket has failed. I'll take the head off and have a look. Thanks to everyone for your input.

Both plugs are looking the same. Both cylinders are working as I pulled off the spark plug covers when it was running. Smoke still absolutely pouring out of the right hand cylinder exhaust. So it's definitely the one cylinder that's the problem. Going to have to take the cylinder head off. Thanks for all the advice.

The oil level is correct. If I take the breather off the back of the carb and block the hole up what does that achieve? Sorry but I'm not familiar with that . Thanks for the input.

Thanks for your thoughts spudulike. There's no water or diesel in the fuel and both cylinders were almost exactly the same in compression one was 120psi and the other was 125psi. In the leak down test both returned 20%ish leak which is quite good for an engine 20 years old. Yes all jets were checked when the carb was off. Choke isn't stuck moving freely. Quite a puzzle this one.

Sorry roys forgot to mention that I have adjusted the valve clearances on both cylinders. My first suspicion when the problem arose was obviously a blown head gasket but can an engine return a reading of 125psi with a blown head gasket? I'm reluctant to take the head off to find out but maybe it's the only thing left to do. The carburettor is the Nikki type with fixed idle mixture valves and limiters in the top so that doesn't help as you only have a very limited amount of adjustment and they come to a stop. Maybe they have moved. If I forced them beyond the limitation does anyone know whether I would break something? Also could a bad idle mixture cause the smoking? Many thanks.

Hi everyone, I have a problem that's driving me mad. I have a Cub Cadet ride-on mower powered by a Vanguard V twin 20hp Briggs and Stratton engine. It will only start with a squirt of easy start and then runs normally for about 1 minute and then starts to smoke quite badly. Bluish or white smoke. I have done a compression test and both cylinders have 120 - 125 psi. A leak down test shows only 20% loss. So all appears to be good. Carb has been stripped down and thoroughly cleaned. Both magnetos have been adjusted. Good spark at one plug. The other had no spark until I removed the kill switch wire. So it does have a short somewhere but that wouldn't cause the smoking or reluctance to start. I'm fairly good with the running of small engines but this one really has me beaten. Any advice or ideas would be much appreciated. Many thanks - Richard

adw when you say a leak down test is that a compression test on each cylinder? If so I think I can buy one that screws into the plug holes for about 25 quid. I removed the breather pipe completely and the plugs are still getting oily. I was wrong when I said black smoke coming from the exhaust it is actually grey smoke. I've just taken the carburettor off for the fourth time and will clean it again. while it's off I can have a look at the crankcase breather. Thanks for all the help.

It's definitely oil. The breather pipe that goes into the back of the air filter is badly deteriorated. I'm trying to get a new one online. Could that be an issue?

If it is just a massively rich mixture how do I remedy that? The carb has two mixture adjusters on the top that have limiter buttons fitted. One of these is intact so I put it in the middle, but the other is missing. Do I screw that one in until it seats and then back it of one and a half turns as is normally suggested?