Prob with Perkins 4-108s

[jecuk]

So our twin Perkins are serviced every year and the last was just done. Both before and after the service we have noticed that the port engine in reverse just doesn't seem to rev. At low speed in the marina it goes into gear and seems to work fine. But when we need that big pull to turn to bow in on the river it just doesn't seem to do it. Goes into gear but doesn't seem to generate any torque through the prop.

Gearbox oil is fine. Cables are adjusted. Seems to me like the gearbox internals are dying. While we always wait between forward and reverse, they have been in the boat for a long time and it is hard to know how they have been treated.

Thoughts or ideas?

 

[NorthUp]

Assuming they are hydraulic gearboxes, try and arrange for an oil pressure gauge to be fitted.
If they are borg warners, you should have equal pressure running both ahead or astern prob about 200 -250 psi (from memory but can be checked), with a dip in pressure as they go into gear. Unequal pressure indicated internal leaks at the clutches, both directions low-worn oil pump, oil too hot, etc.
Lots of other possibilities, but the oil pressure check is the first for possible diagnosis.
Edit- does the engine rev up like a car with a slipping clutch when you go astern or do the revs not go up on the engine?

 

[jecuk]

Thanks for the reply. Seems more like a slipping clutch to me.

 

[Cliveshep]

Most Perkins engines seemed to have been mated with TMP gearboxes. TMP are in Weybridge operating from the guy's house these days but he offers a good rebuild service at reasonable rates if you can get the box to him. Your problem is almost certainly slipping clutches, it won't get any better so consider hoiking the lump out onto the side and removing the gearbox and taking it in to him. It takes about an hour to disconnect a 4.108 ready for a crane to lift it, even a digger or forklift can lift it out easily or you can just disconnect everything, jack it up and wedge it up and remove the box in the boat. This is not a load of old cods, I've done it twice myself on my own and took the box in for repair on two separate boats. for DIY repairs see here:

http://www.thameswaymarineproducts.co.uk/diy.htm

For service see here:
http://www.thameswaymarineproducts.co.uk/index.htm

Off you go then!!!

 

[jecuk]

Thanks. No it is definitely a BW Velvet drive 72-C hydraulic box.

 

[rich]

Slipping cones then, still got to get the box out.

 

[jecuk]

Will be replacing engines at the end of this year so not sure I really want to spend too much on these particularly with taking the engine out. The other engine is fine. May just have to compensate for it and live with it.

Really appreciate all the advice on here though.

 

[burgundyben]

Did you check the oil level with the engine idling? Worth doing that.