Engine Dies after 2-4 minutes of running

[jharville]

Hi,

I just did a partial rebuild on my Super Dexta b/c it had gradually been burning more and more oil over the last year or so. The tractor was in a running condition when I tore it down...it just burned lots of oil and required ether to start it. I just got it back together tonight after replacing sleeves, rod bearings, pistons and rings and head gasket. I can get it cranked and it runs pretty well for 2-4 minutes. During this time it runs with a clear exhaust and a consistent idle. After the 2-4 minute mark it seems to die quite rapidly in the span of 5-8 seconds. During this 5-8 second period the exhaust gets smoky(although I could not tell the color b/c it was dark out) and a stream of water shoots out of the radiator overflow. If I wait a few minutes I can start it up again and the process repeats all over again. I'm suspecting something is going on with the head gasket that is triggered by the thermostat cutting on, but so far I haven't been able to find any forum posts with my exact symptoms. Can anyone provide any insight?

Thanks,
Jason

[Brian]

Jason,

The first thing that comes to mind with your symptoms is what sleeves did you use? A few years ago we went through a period of people having the exact same problem and it was due to using the wrong engine sleeve.

Originally, all Dexta engines had to be re-bored when new sleeves were fitted, this was because the sleeve was a press fit and distorted when being fitted. That was normal practise. In later years engine workshops got the idea that just honing new sleeves would be OK and a number of people suffered problems of partial seizure when the engine was run.

Today people can get "pre-sized" sleeves for M-F Perkins engines and this seems to be fine but I would still check new sleeves to see they are the correct size when fitted.

[jharville]

Oh boy, not what I was wanting to hear. I used the sleeve/piston kit listed here: http://www.ytmag.com/cgi-bin/store/mode ... es&r=mcats

I was under the impression these were finish bored and ready to go but maybe I'm wrong.

-Jason

[blue32]

Hi Jason, it can well be as Brian tell,s but are you sure of it,s not any air coming into fuelsystem any place? and concern of water flow over... it also can be alot dirt in the radiator or coolingsystem...bad thermostat or waterpump too... well if it was me, I would check this at first.

mikkel

[jharville]

Funny you mention that. After further experimentation I discovered that the engine was promptly dying after the tractor started overheating. I remembered that my last job before the rebuild was a full day of bushhogging. I discovered an almost completely clogged radiator. I sprayed it clean and removed the thermostat just to rule it out. I just harrowed for 45 minutes with no issues....which is a huge relief. I didn't expect over heating to be the cause because I've never had the engine stop running when overheating. Maybe this new symptom is due tothe tighter engine.