very low compression, non starter

[rotrax]

"

I hate to say this and I dont like it but...........

If you really are having problems getting it to fire........ easy start.

Not many people like it and I'm in that group, but, it will get the engine to run then you can as has been suggested give it a good hard run."

Pragmatically-

I wouldn't use Easy Start routinely but the tales of it damaging engines are very mixed/apocryphal.

In truth, it's only ever used on sick/dead/dying engines which sometimes expire soon after. It's easy to say it's the ether, QED, wot dun it.

I have a diesel book from the sixties, mainly lorry engines. In the section on cold starting there are described builder fitted cold start mechanisms for applying ether to the manifold. So ether per se is not death to engines?

Nick

Hi, I had a Volvo 2003 and the cold start mechanism in the injector pump was faulty. A TINY-half second-squirt of easy start would get it going every time,even in minus tempratures. Once away it was fine for the rest of the day. As other posters have said, squirting away into the manifold while cranking is NOT the way to use it. The advantage in the case of my 2003 Volvo was the reduction in wear and tear on the starter motor and associated bits. Its horses for courses,it worked for me. Also, a retired RN engineer told me that in severe condition ether was often used to start diesel harbour launches and workboats when he was "in". It was poured across the intake gauze,the cap of the bottle being used for this. I have been involved with the repair of small engines for 45 years and have never come across an engine damaged by the use of ether or easystart. I have heard some horrendous noises coming from engines where it has been squirted directly into a cranking petrol engine though!

 

[niallw]

Low compression problem solved (hopefully)

In the six/seven weeks since i started this thread, ive taken engine off boat and too a Yanmar dealer/workshop (not a marine dealer, cos they put huge markup on everything, but a industrial dealer.

It seems the main problem causing the low compression was a valve seat worn well past its limit. The valve itself was OK, just needed a cleanup to remove carbon but valve seat worn to 0.08" when its recommended max wear was 0.035".

Thanks to all contributers, it seems the wet compression test is not fail safe method of eliminating valve (or valve seat wear) afterall. It could be I inadvertantly sealed the valve seat when i first tried to crank the engine (while operating decompression lever) without first replacing the fuel injector, causing gear oil to splash around inside cylinder, doh.

 

[niallw]

Despite my doubts it seems you were right about low comp problem.

sounds much more likley to be the valve seats leaking due to pitting, when the oil is added it creates a better seal. they are renown for getting pitted and i have many scrap valves from gm engines. Yanmar sell more valves than any other rebuild part for the gm engines.

As the exhaust port is corroded up with carbon the head has to come off to remove it, do the valves at the same time, the engine recon company can put new valve seats in which will reset the valve height back to factory level thus resoring any loss of compression due to any previous valve grinding.
The rings are far less likley to be a problem unless they have been damaged, the bore however does also glaze up badly when the engine is run at slow speed with little load for long periods.

Hope this is helpfull.

Steve

Hi, so main problem was worn valve seat. Now I just have to get the beast reinstalled.

 

[Searush]

Well done, good luck, work it hard from time to time & enjoy your sailing!

I was told to use oily rags to block air inlet & exhaust outlet to reduce condensation over winter. Condensation can cause sticking valve or rings - I realise that neither of these problems were yours (this time!)

 

[Scotty_Tradewind]

It's really interesting as a 'layman' to follow these threads. So much to learn.
Best of luck on the reinstallation and with getting her up and running.

When laying up for the winter are there any other little snippets of info' to stop internal corrosion?

 

[pvb]

If you have to use a start aid, WD40 is better, it contains a propellant ( I think its a propane type gas).....

It was in olden days, Stu, but the propellant was changed some time ago to carbon dioxide.

 

[RMC]

With regard to reducing internal corrosion I was advised to hand crank the engine until the start of the compression stroke thus both valves are closed, and leave it there for the Winter layup. This obviously will only work on a single cylinder engine.