Westerbeke 46 Cylinder Compression

[zboss]

Hello,

I recently had a compression test done on my engine, a westerbeke 46. The compression came back within a wide range. #2 had a 520 and #4 had a 445. The engine starts up immediately and runs fine, except for some overheating caused by a cascade of cooling issues, which is being fixed.

This was a cold test. I have heard rumors that the westerbeke normally has wide compression ranges before warming up... is this true?

Anyone have experience with the engine in this regard - is it anything I should really worry about? I wish I had the previous engine results because it would be nice to know if there is a trend or if the engine has always had these compression issues.

[djmarchand]

Forget about compression. It is a meaningless and highly variable number. If the engine starts easily from cold your rings and valve guides are good.

David

[bobconnie]

A Valve adjustment may raise the compression a little, it sure can't hurt, if she starts well cold, thats all I would do to mine and it's what I would suggest to a customer ! Just my 2 cents

[Celestialsailor]

Westerbeke is a marinizing company...not an engine company. If it's a Westerbeke W46, then it is based on a Mitsubishi 4DQ5. Number 4 cylinder was the one on mine which had water intrusion caused by a back up in water flow out the exhaust. I have a center cockpit and the exhaust run is long with a double loop. I rebuilt my engine by ordering parts direct from a distributor for Mitsubishi. You cannot tell them it's a W46 because they have a proprietary deal with the bandits at Westerbeke. You have to tell them it's a 4DQ5. Hope this helps.

[Blue Stocking]

to Celestialsailor To add to above: that is the 127 cu.in block.

[zboss]

Originally Posted by Celestialsailor

Mitsubishi 4DQ5. Number 4 cylinder was the one on mine which had water intrusion caused by a back up in water flow out the exhaust. I have a center cockpit and the exhaust run is long with a double loop. I rebuilt my engine by ordering parts direct from a distributor for Mitsubishi. You cannot tell them it's a W46 because they have a proprietary deal with the bandits at Westerbeke. You have to tell them it's a 4DQ5. Hope this helps.

Do you know of a good online site for buying 4DQ5 parts?

[Celestialsailor]

Google Westerbeke W46 Manual. You'll see westerbekes online manuals. About 1/2 way down the page will be the W46 owners, parts and Tech manuals. I would attach the links but there site is timing out at the moment.
Any 4DQ5 parts online will most likely be from China. Don't even think about it? Do it the old fashion way...call Mitsubishi America and find a parts distributor nearist you...not a car dealership. Hope this helps.

[tdoster]

I seem to have an issue with rough idle below 900 RPM's. The mechanic said the W46 is supposed to idle at 1000 RPM's. In my case #3 is lower compression than the others. Engine only has like 600 hours on it, but is 27 years old. In all my years, this is the only Mitsu I have dealt with. Any thoughts?

[Blue Stocking]

Mine idles sweetly at 750-800, anything higher and the Hurth crunches when going into gear.