Engine runs rough at idle.

[skipmac]

Have a 30 year old Westerbeke W58, exact same engine as the Perkins 4.154.

Since I've had the boat it runs very rough at idle. If the tach is correct it's idling around 800-900 rpm which is according to spec. Once I rev up just 100-200 rpm it smooths right out.

Engine doesn't smoke or burn oil.

Installed newly rebuilt injectors and if anything it's slightly rougher at idle, but smoother at speed. I was told that the engine could use a valve adjustment. Could that be the problem? Only other idea I have is the injector pump?

[model 10]

Perkins mentions micro adjusting the fuel pump timing in the service manual. I think there is also an advance mechanism in the bottom of the fuel pump that can stick.

[skipmac]

Originally Posted by Guy

Perkins mentions micro adjusting the fuel pump timing in the service manual. I think there is also an advance mechanism in the bottom of the fuel pump that can stick.

Thanks. Will have to dig out my manual to see if I can track that down.

[Stu Jackson]

Just increase the idle. We get that same stuff on most Universals.

[skipmac]

Originally Posted by Stu Jackson

Just increase the idle. We get that same stuff on most Universals.

Well I kind of do that. I made a throttle friction lock for my Edson and when idling give it just a tiny bit of throttle and lock it down. However, not sure if I want to set that permanently as min idle by adjusting the idle screw on the engine. My concern is shifting at a higher rpm would put more strain on the transmission?

[puffcard]

Originally Posted by Stu Jackson

Just increase the idle. We get that same stuff on most Universals.

I also did this to about 1,000 RPMs. Mine is running better now than ever, I also started using Diesel Fuel Supplement Plus Cetane Boost. Seems to help. I have a Westerbeke 50.

[a64pilot]

Valves could do it, need checking anyway if you don't know when it was done last.
I'll get argument on this, but valves wear tight, too tight and a valve leaks, leaks long enough and you need a valve job.
If you have valve train wear, it wears and loosens clearances.
I would not turn my idle up either, for the exact reason you describe, hard on the transmission. I'd do what your doing, just bump the idle up a little until it smooths out.

Bad engine mounts can also allow one to shake more.

[skipmac]

Originally Posted by a64pilot

Valves could do it, need checking anyway if you don't know when it was done last.
I'll get argument on this, but valves wear tight, too tight and a valve leaks, leaks long enough and you need a valve job.
If you have valve train wear, it wears and loosens clearances.
I would not turn my idle up either, for the exact reason you describe, hard on the transmission. I'd do what your doing, just bump the idle up a little until it smooths out.

Bad engine mounts can also allow one to shake more.

Thanks. No telling how long since a valve adjustment so probably needs doing anyway. Never done one but doesn't seem like it's too complicated. Any gotchas to worry about?

Mounts are new so that shouldn't be an issue.

[GordMay]

Originally Posted by a64pilot

... I'll get argument on this, but valves wear tight...

Indeed.

Valve clearances will get tighter as the seats and valves wear ("recession"). As wear happens, the valve seats farther and farther into the head seat, using up the valve "clearances".
However, once the initial seating has bedded in, there seems to be very little further movement (tightening).

“Valve recession occurs when wear of the valve or seat inserts in an automotive engine has caused the valve to sink or recede into the seat
insert...”
➥ http://eprints.whiterose.ac.uk/778/1..._Recession.pdf

[a64pilot]

Originally Posted by skipmac

Thanks. No telling how long since a valve adjustment so probably needs doing anyway. Never done one but doesn't seem like it's too complicated. Any gotchas to worry about?

Mounts are new so that shouldn't be an issue.

Just follow directions, on mine since the serpentine pulley covers the original and the marks can't be seen, I remove the injectors and use a soda straw to determine TDC, A soda straw can't damage anything, don't use something that can break off like a shish kabob stick. You have to have a direct combustion engine for this to work, if you have a precombustion chamber, you can't get to the piston through the injector hole
TDC on compression is easy to determine as the valves will be loose. Injectors out also make it real easy to turn, and if you take them out every once in awhile they don't get stuck, leave them in for years and they can be tough to get out.
I like using a go/ no go gauge, its a feeler gauge with a step built in, so you will say have a both an 8 and a ten thousand thickness, if you want 8, adjust so there is a tiny drag with it on the 8 thickness and of course the 10 will not go through.
A tiny bit loose is better than a tiny bit tight, too tight will cause a valve to "burn" that is when the engine gets hot, the clearance may go away and the valve be a tiny bit open and it will leak combustion gasses and over time it will leak.
Be real sure to adjust at the engine temperature the manual says, I bet most are cold, and that means hasn't been run in a day to me, a few have to be done hot, but that I believe is not common.

[sailah]

I just set the lash on my Westerbeke 44B although I think they are different engines altogether.

My service manual says to align the timing marks on the crank pulley. Since mine is V drive that's buried in back. I had to use 220 sandpaper to lightly sand the pulley until I could see the mark, very faint. I used a 27mm (?) socket with ratchet to turn the crank. I had the injectors out so it turned easily.

Check the lash with feeler gauge set. Pretty self explanatory, mine is 0.25mm on both intake and exhaust. When I did mine, all were spot on except one, which I ended up having to pull the head for. So I'll be doing it again.

The manual should give the firing order, simply rotate the crank 180 degrees and do the next one. In my case it is 1-3-4-2 so the first alignment mark is used for 1 & 4 and the alignment mark 180 degrees from that is for 3 & 2.

One tip is to hold the adjuster screw exactly where you want it with a little backpressure while you snug up the nut. That will prevent you from creeping on your measurement and check again after you snug them up to be sure you hit your mark. I check for a light drag with the feeler gauge as I'm pulling it through.