JP hunting at idle

[tommylad]

Just thought I'd share my experiences of finally sorting the hunting problem my engine has suffered from when hot at idle. It used to idle beautifully around 30 years ago, but gradually started hunting as the years have gone by. I gather this is a problem for quite a few JPs - and I know some on this forum have given very useful advice on it. I'd always assumed it was because of worn bearings in the governor, so when I rebuilt it 3 years back I was surprised to find the governor in spot-on condition. I did replace the tension spring and clean out & re-lube the bearings on the bell crank, but surprise surprise when the job was finished the hunting was still present. More recently, I've checked some of the setup of my fuel pump, and whilst in there, decided to oil some moving parts which I understood should be lubricated by diesel, but I thought why not? As I oiled the rack and plungers, I noticed that the movement of the rack did free up a little, and to my great delight I've found that the hunting is now gone! I'm so pleased to have my metronomic grand father clock back at last!! I'd encourage anyone with the same issue to not fear going into the pump to try this fix, as it's very easy. I'd always been reticent to open up the pump but if you're careful with cleanliness then you really shouldn't fear taking the inspection cover off the side of the pump and squirting a bit of oil around in there. I used 20 grade mineral oil. If you have a very compact screwdriver the cover can probably be taken off with the pump in situ, but I removed my pump to do the other checks, which does make access easier.

 

 

[cuthound]

30 minutes ago, tommylad said:

Just thought I'd share my experiences of finally sorting the hunting problem my engine has suffered from when hot at idle. It used to idle beautifully around 30 years ago, but gradually started hunting as the years have gone by. I gather this is a problem for quite a few JPs - and I know some on this forum have given very useful advice on it. I'd always assumed it was because of worn bearings in the governor, so when I rebuilt it 3 years back I was surprised to find the governor in spot-on condition. I did replace the tension spring and clean out & re-lube the bearings on the bell crank, but surprise surprise when the job was finished the hunting was still present. More recently, I've checked some of the setup of my fuel pump, and whilst in there, decided to oil some moving parts which I understood should be lubricated by diesel, but I thought why not? As I oiled the rack and plungers, I noticed that the movement of the rack did free up a little, and to my great delight I've found that the hunting is now gone! I'm so pleased to have my metronomic grand father clock back at last!! I'd encourage anyone with the same issue to not fear going into the pump to try this fix, as it's very easy. I'd always been reticent to open up the pump but if you're careful with cleanliness then you really shouldn't fear taking the inspection cover off the side of the pump and squirting a bit of oil around in there. I used 20 grade mineral oil. If you have a very compact screwdriver the cover can probably be taken off with the pump in situ, but I removed my pump to do the other checks, which does make access easier.

 

 

 

The lack of lubrication is because of the ultra low sulphur diesel used today (<0.001% sulphur content). Sulphur was a great lubricant. The bio content helps a little but doesn't compare to the lubricity of the  old 5% sulphur content of 30 years ago.

 

You can buy diesel additives to increase the lubricity of diesel I believe.

[David Mack]

Unusual setup for a JP. Looks like a marine engine (with marine water cooled silencer and flywheel on the right end), but fitted with a remotely mounted hydraulic gearbox. What's its history?

[tommylad]

3 minutes ago, David Mack said:

Unusual setup for a JP. Looks like a marine engine (with marine water cooled silencer and flywheel on the right end), but fitted with a remotely mounted hydraulic gearbox. What's its history?

It's a marine auxiliary engine (1962) - came from an isle of mann ferry (was used for pumping water for washing the decks), so dry sump, water cooled silencer, even lloyds stamped, but with the industrial crank and no gearbox. Odd to think it's been in the narrowboat for longer than it was in the ferry! 

38 minutes ago, cuthound said:

 

The lack of lubrication is because of the ultra low sulphur diesel used today (<0.001% sulphur content). Sulphur was a great lubricant. The bio content helps a little but doesn't compare to the lubricity of the  old 5% sulphur content of 30 years ago.

 

You can buy diesel additives to increase the lubricity of diesel I believe.

Interesting comment. Are we perhaps causing damage to our irreplaceable pumps/injectors by running modern fuels in them? Has anyone else got experience/knowledge of additives which might help? 

[MtB]

Hmmm nice video, sounds lovely! 

 

My Gleniffer ticks over about the same speed and is tending to hunt nowadays which I find irritating beyond all reason. It also tends to go out sometimes when I wind the speedwheel down to tickover. It has the same injector pump as yours. I'll try the same fix, thanks! 

 

 

[tommylad]

17 hours ago, MtB said:

Hmmm nice video, sounds lovely! 

 

My Gleniffer ticks over about the same speed and is tending to hunt nowadays which I find irritating beyond all reason. It also tends to go out sometimes when I wind the speedwheel down to tickover. It has the same injector pump as yours. I'll try the same fix, thanks! 

 

 

Yes, all sounds familiar! And yes, it's just not funny how annoying it is!! 

[cuthound]

22 hours ago, tommylad said:

It's a marine auxiliary engine (1962) - came from an isle of mann ferry (was used for pumping water for washing the decks), so dry sump, water cooled silencer, even lloyds stamped, but with the industrial crank and no gearbox. Odd to think it's been in the narrowboat for longer than it was in the ferry! 

Interesting comment. Are we perhaps causing damage to our irreplaceable pumps/injectors by running modern fuels in them? Has anyone else got experience/knowledge of additives which might help? 

 

When I worked for BT they had over 6,500 diesel engines standby generators, mainly relatively new but some dating back to the 1950's and 1960's.

 

They did extensive testing and found that some of the older ones required additional lubrication when run on ULSD to prevent excessive wear of the fuel pumps, injectors were not affected. A fuel additive to increase lubricity was used for these specific engines. 

 

However when the 7% bio ULSD became generally available it was found that the lubricity additives could be dispensed with because the bio content improves lubricity.

[MtB]

4 hours ago, cuthound said:

When I worked for BT they had over 6,500 diesel engines standby generators, mainly relatively new but some dating back to the 1950's and 1960's.

 

Any Gleniffers or JP2s?

 

 

 

[David Mack]

9 hours ago, MtB said:

 

Any Gleniffers or JP2s?

 

 

 

Lots of CEs I believe.

[Tony Brooks]

And from images I was shown while preparing the "multi-skilling" BT diesel course a few in London (and possibly other large cities) that looked as if they would have powered that ferry Tommylad was talking about.

[cuthound]

15 hours ago, MtB said:

 

Any Gleniffers or JP2s?

 

 

 

 

Sadly not.