6.354M Idle Speed

[Tom.B]

For the past couple of months, Skinny Dippin' has been dropping to such a low idle that the motor would shut off during docking. Kind of a hassle. It turns out the idle screw is stripped. Perhaps by me, perhaps not, but that isn't the topic. I have read every manual I have (and I have them all) on my 6.354M 130hp Perkins motor, and all it says is that different applications call for different idle speeds with no chart, graph, or list about what the application and subsequent idle speed is for said application.

Can someone tell me what I should set my idle speed to? And before you say it... YES... I was a member of BoatDiesel.com, but my membership ran out. I hardly want to invest $25 for this small piece of info. So if you could help a brother out, it would be most kind.

Tom-

 

[Duvie]

I have the 200 Perkins 6.354m. I had the same issue trying to find the idle speed information. After posting on boat diesel I got several replies which ranged from 650 to 750 rpms. Mine were running about 450 which created lots of vibration. Brought them up close to 650 and they are much happier. Leon

 

[Woodsong]

I've got the 6.354 Perkins in our Monk. I can get that thing to idle ridiculously low- like 400-450 RPM's but never so low that it ever cut off. At low RPM's it vibrates the boat like crazy. I find that if I set the throttle to RPM around 600-700 RPM's that the boat and engine seem happy.

 

[FF]

When engines are mfd , the crank/rods are balanced to put the shake in an area the engine is not normally operated .

Usually below normal idle , and above operating RPM , if they can.

Sounds like 400rpm was not contemplated as idle speed.

 

[Tom.B]

Wow... All these numbers seem much higher than where it was before. IIRC, she was previously set to 350-450. My worry is setting the idle at 600-ish with add unnecessary wear on the transmission clutches going into and out of gear at the higher RPM's. But hey, that was only a suspicion.

 

[Nomad Willy]

Tom,
If you put your transmission in and out of gear quickly (especially on manual gears) no excessive wear or problems will result.

Extremely high wear in the damper plate can result from too low an idle. The damper plate has springs arranged radially to absorb much of the high torsional forces the diesel engine presents to the drive train. Too much abuse and the little springs crunch up, break and fall into a heap. That can leave you dead in the water. Lots of fishermen (especially trollers) have experienced this fate. A higher idle can reduce the chances of having damper plate failure tremendously. Also there are a number of damper plates that have cleverly designed and shaped plastic shock absorbers that may be better. I had one in my previous boat that had a 3 cyl engine.

I adjust my idle speed so that when the boat is cold I can untie my lines and get underway immediately w an idle speed that assures that the engine won't die when I shift gears. When the engine has fully warmed up my idle speed is over 1000rpm but I have a 3000rpm engine. On a 2500rpm engine that would be equivalent to 800rpm. I have experienced no downside, heard of no downside or read about no downside to a high idle until you posted this thread. I too was on Boat Diesel but was surprised that I didn't use it much. Many boats were over propped when most of our trawlers were made and so I'm sure many owners turned down the idle speed to keep harbor/docking speeds in check. Not over propping, turning the idle speed up to 1/3 of rated rpm and shifting quickly will solve these problems.

 

[JAT]

Both of my 6.354's idle at about 650-700 rpm.... and they are happy there.

 

[psneeld]

Most diesels I've ever run are in the 600-700 rpm idle range.

 

[Nomad Willy]

If one has soft engine mounts the boat may be smooth but the damper plate may still be taking a beating. I also suspect that a lot of gear rattle could be caused by the interaction of the damper plate springs and the clearance of the gears. I had a Kansaki light weight aluminum cased gear that made an awful racket and I believe it to be caused by this.

 

[twiisted71]

Mine is around 600 maybe a shade over. That is as low as I could go with the engine at operating temp before the shakes concerned me. This is just what I like. Still get nice smooth shifts and its high enough that the engine doesn't lope when in gear.

 

[Tom.B]

It also makes me wonder that idle speed maneuvering would be kinda faster than it used to be. I'd need to relearn some basic handling if I am going twice as fast as I used to go when at idle speed but in gear.

 

[Nomad Willy]

Tom,
Just put it in and out of gear as necessary to achieve the speed desired. As long as one sifts smartly and quickly the clutches won't suffer from being used. AND you can go as slow as you want.
Does a typical trawler respond to rudder at 1 or 2 knots w/o propwash?

 

[Edelweiss]

Did you reset the antistall device when you adjusted the idle speed. That may explain your engine stopping unexpectedly:

C.A.V Rotary Pump - 6.354 M

(1.) Loosen locknut and unscrew anti-stall device body two complete turns.
(2.) Adjust idle speed to 625 RPM with idle adjusting screw.
(3.) Screw down anti-stall device until engine speed increases slightly.
(4.) Turn back one half turn and lock in place by tightening locknut

 

[FF]

"idle at 600-ish with add unnecessary wear on the transmission clutches going into and out of gear at the higher RPM's."

Very little wear as the prop is in a fluid and slips easily.

Not like a truck on a hill were clutch slipping is done to increase the torque to start.

The spinning MASS of the drive train is why shifting from Fwd to Rev is done at lowest speed.

Larger boats that require manuverability will have a shaft brake to stop shaft between shifts.

 

[Tom.B]

Did you reset the antistall device when you adjusted the idle speed. That may explain your engine stopping unexpectedly:

C.A.V Rotary Pump - 6.354 M

(1.) Loosen locknut and unscrew anti-stall device body two complete turns.
(2.) Adjust idle speed to 625 RPM with idle adjusting screw.
(3.) Screw down anti-stall device until engine speed increases slightly.
(4.) Turn back one half turn and lock in place by tightening locknut

Hmmmm....

(About where is it on the pump?)

 

[Edelweiss]

Hmmm. Good question. This was on a service bulletin from NC Machine, dated 1977. NC was the Perkins dealer in Seattle then. It was stuck in the front of my Perkins engine service manual. The dealer did some tweaking on the engines when we bought the boat and left some manual updates with us. Below is the rest of the information. Unfortunately, there are no pictures. It doesn't copy and paste very well either.

I haven't had to adjust mine, but both do idle at around 600 RPM's. After rereading this I'm not sure if they are saying there are three different types of pumps or three different points to adjust the idle setting at??
----------------------------------------------

C.A.V. Rotary Pump Idle Adjustments
On rotary pumps there are three types of adjustments. The first is a spring loaded screw. The second is on the reversible governor head which consists of a setscrew and locknut. The third is on the governor housing on a mechanically governed type pump and consists of a nut and setscrew.
• On the first type turn the adjusting screw clockwise to increase engine speed or counter clockwise to decrease.

• On the second type undo the locknut and set the required speed.
This must be done in conjunction with setting the anti-stall device.

• On the third type, loosen the locknut and set the required speed.

 

[Tom.B]

I saw that in my book too... Could barely understand the point.

 

[Baypoint]

If your idle speed has been dropping with no adjustments i suspect dirty fuel filters. Change your Primary first and then your secondary. That may solve the problem

 

[Tom.B]

If your idle speed has been dropping with no adjustments i suspect dirty fuel filters. Change your Primary first and then your secondary. That may solve the problem

It hasn't been dropping... And I have been changing filter very often because of a previously mucky tank that has since been cleaned.

 

[RickB]

If your idle speed has been dropping with no adjustments i suspect dirty fuel filters.

If the idle speed dropped due to dirty filters, the engine could never go above idle.

 

[Edelweiss]

It hasn't been dropping... And I have been changing filter very often because of a previously mucky tank that has since been cleaned.

--------------------------------------
When my primary filter is about due for change, I will notice a slight surging in the engine, about 100 rpm's or so at cruising speed. You have about 2 hours after that to change the primary filter before you begin to loose power.
LB