Petrol chainsaw smoking and overheating

TudorBlue · Post by **TudorBlue** » Fri May 07, 2021 5:06 pm

Need a spot of advice with a Gardentec petrol chainsaw. It overheating with quite a lot of smoke coming from the exhaust. I've taken the chain and bar off but it's still the same. It gets really hot. Need help and advice with it. It was originally bought from Aldi in the UK. Could it be the mix of fuel? I've checked the air filter and it's been blown out but it was clear anyway. Any help and advice with this will be really much appreciated.

Hitch · Post by **Hitch** » Fri May 07, 2021 5:27 pm

Have you been mixing the correct fuel/oil ratios accurately? Has it been sat up unused over the winter and now its smokey?

I'd be inclined to give the tank a swill out with some petrol, then refill with fresh fuel/oil mix and see what happens. When refilling always give the can a shake first too, helps the petrol/oil mix up again if its been sat.

Pop the spark plug out too and have a look at its condition, that gives some indication to how an engine is running with regard to air/fuel mixes too.

Dave54 · Post by **Dave54** » Fri May 07, 2021 5:29 pm

Brake's not on is it?
Could be the two stroke mix. Too much oil can apparently cause overheating by making the fuel air mix too weak. I'd have thought it'd have to be working fairly hard though for that to be a factor.

TudorBlue · Post by **TudorBlue** » Fri May 07, 2021 5:31 pm

It’s 25/1 mix of petrol to oil. Had fuel left it from last year but if I remember rightly it was overheating/ Smoking when I last used it. The spark plug is good.

Dave54 · Post by **Dave54** » Fri May 07, 2021 5:33 pm

As Hitch says, wash the tank out and use fresh mix.
Modern petrol doesn't store well, because of the ethanol added to it.

kellys_eye · Post by **kellys_eye** » Fri May 07, 2021 5:48 pm

Clutch slipping? Brake not releasing properly? Too little oil in the fuel? Too MUCH oil will cause a smokey exhaust (obviously) but what makes you think it's running hot as they do run 'hot' normally.

Check also for the casing 'fins' (around the cylinder head) being clogged with sawdust too.

dewaltdisney · Post by **dewaltdisney** » Fri May 07, 2021 8:17 pm

I suspect it is a carburretor issue. If it is overheating then this is an indication that it is not combusting properly. The 25:1 oil mix provides good lubrication so if the motor cooling fins are clear of crap then the carburettor is the thing to look at. You can buy a new one from eBay for under a tenner.

DWD

kellys_eye · Post by **kellys_eye** » Fri May 07, 2021 8:57 pm

dewaltdisney wrote: ↑Fri May 07, 2021 8:17 pm You can buy a new one from eBay for under a tenner.

Yes. A good move. Trying to fix a dodgy carb isn't worth the effort when a replacement is so cheap.

Check out YouTube for many good ideas on chainsaw servicing or repairs too - there are many good vids.

APDIY · Post by **APDIY** » Sat May 08, 2021 4:40 pm

I've had exactly the same problem with my Gardentec chainsaw.
It got so hot that it stopped working - not seized.
When it cooled down, it started up easily and ran until it got hot
and stopped again.
I'd not run it long enough for the carb. to be worn or have I
damaged the butterfly on the carb.
At 25;1 the stated mix seems very oil-rich compared to others I've
used that took 40;1 or 50;1.
I've checked the web-site and the 25;1 mix is confirmed.

Dave54 · Post by **Dave54** » Sat May 08, 2021 5:18 pm

APDIY wrote: ↑Sat May 08, 2021 4:40 pm I've had exactly the same problem with my Gardentec chainsaw.
It got so hot that it stopped working - not seized.
When it cooled down, it started up easily and ran until it got hot
and stopped again.
I'd not run it long enough for the carb. to be worn or have I
damaged the butterfly on the carb.
At 25;1 the stated mix seems very oil-rich compared to others I've
used that took 40;1 or 50;1.
I've checked the web-site and the 25;1 mix is confirmed.

I actually bought one, but took it back because it was very hard to pull over compression. I've got four bits of petrol kit, and none of them are anything like that hard. I could see it busting the pull start mechanism.
I run them all on Aspen fuel now. Premixed. So far so good. Even the older kit starts pretty well straight off after being left with fuel in it.
The fuel's expensive, but the lack of hassle makes it worthwhile IMO.

TudorBlue · Post by **TudorBlue** » Sat May 08, 2021 5:51 pm

APDIY wrote: ↑Sat May 08, 2021 4:40 pm I've had exactly the same problem with my Gardentec chainsaw.
It got so hot that it stopped working - not seized.
When it cooled down, it started up easily and ran until it got hot
and stopped again.
I'd not run it long enough for the carb. to be worn or have I
damaged the butterfly on the carb.
At 25;1 the stated mix seems very oil-rich compared to others I've
used that took 40;1 or 50;1.
I've checked the web-site and the 25;1 mix is confirmed.

So you think the fuel to ration oil may be too much oil? It says 25/1 on the saw itself so that’s how I’ve mixed it. I’ve tried changing lubricating oil and it’s still the same, the carb is good. Is it worth changing the fuel mix ratio?

kellys_eye · Post by **kellys_eye** » Sat May 08, 2021 7:27 pm

Sure about the way you mix the fuel? What about the oil used for the mix? 2-stroke oil or just 'any old oil'? Sorry if this is sucking eggs but we need to know!

dewaltdisney · Post by **dewaltdisney** » Sat May 08, 2021 8:07 pm

I am very careful on mixing my 40:1 two stroke fuel. I have a measuring jug and one of those medicine measure cups for the oil. For 40:1 it is 25ml of oil per litre, for 25:1 it is 40ml. As a 2 stroke engine runs without an inbuilt oil feed it is lubricated and cooled by the oil which acts before it is burned off by the fuel burn. It lubricates and cools the piston and upper cylinder walls on its travels. Why your machines ratio has to be so oil rich is strange and a high oil mix will mean a lean petrol mix to burn which in turn can cause overheating. That is why I was suggesting the carb was perhaps faulty but it could also mean you are too oil rich. I think you should experiment by reducing the oil ratio from 40ml to 30ml (say 8ml for 1/4 litre) and see what effect that has. The oil will still be present so for experimental runs it should be fine.

DWD

TudorBlue · Post by **TudorBlue** » Sat May 08, 2021 10:02 pm

dewaltdisney wrote: ↑Sat May 08, 2021 8:07 pm I am very careful on mixing my 40:1 two stroke fuel. I have a measuring jug and one of those medicine measure cups for the oil. For 40:1 it is 25ml of oil per litre, for 25:1 it is 40ml. As a 2 stroke engine runs without an inbuilt oil feed it is lubricated and cooled by the oil which acts before it is burned off by the fuel burn. It lubricates and cools the piston and upper cylinder walls on its travels. Why your machines ratio has to be so oil rich is strange and a high oil mix will mean a lean petrol mix to burn which in turn can cause overheating. That is why I was suggesting the carb was perhaps faulty but it could also mean you are too oil rich. I think you should experiment by reducing the oil ratio from 40ml to 30ml (say 8ml for 1/4 litre) and see what effect that has. The oil will still be present so for experimental runs it should be fine.

DWD

Same here, Ive got a mixing jug, could 25/1 be too rich? It says 25/1 in the instruction manual and as I said, I blew the filter out with an airline, wasn't too bad anyway

APDIY · Post by **APDIY** » Sun May 09, 2021 11:41 am

kellys_eye wrote: ↑Sat May 08, 2021 7:27 pm Sure about the way you mix the fuel? What about the oil used for the mix? 2-stroke oil or just 'any old oil'? Sorry if this is sucking eggs but we need to know!

Thanks for that reminder that in these days of highly specific oils it may be even more critical to use the correct type
of oil as advised in the User Manual.

I use 2/ oil for the mix, with fresh petrol, and
Chain oil for that reservoir
And I don't forget the lubrication via the port near the end of the blade.

As the motor and chain assembly heat up, it's vital to check the chain tension.
A slack, or an overtightened, chain is not only a source of harm to the equipment but a danger to the operator.