Pulsing idle question

[edrrt]

A friend wants to seek his 2011 TL240, 2k hours and while it runs smoot full throttle it idles rough. Sort of pulses or surges steadily about 60 times a minute. You can still perceive it at medium throttle but it's less noticeable. I opened the air filter and it was completely packed solid with dirt. The inner element was intact and while dirty it didn't look horrible inside. No smoke. Starts easy. Coolant was clean but very low. Looking at the dates on the filters it's been a year and probably 500 hours since last service. Is anyone familiar with the pulsing at low RPM's in these small diesel engines? Doesn't indicate that the engine got dusted and the injectors are clogged, plugs fuel filters? Something more insidious? He is going to have a mechanic service it and take a look at it as he was somewhat embarrassed but I'm wondering if I should walk away from this machine.

 

[SkidRoe]

Pulsing idle is usually something to do with the governor in the injection pump. It is more of a nuisance than a problem. Some engines just do it more than others. Most engines that do it will exhibit this problem when they are cold and then it settles down as they warm up.
Is the injection pump an inline or rotary? If it is an inline, it may run an independent oil sump, and you may want to consider changing the oil in the pump.
If still persists and you really want to do something about it, the injection pump will need to go to a diesel shop for service.
HTH - SR

 

[mmsllc]

Pulsing idle is usually something to do with the governor in the injection pump. It is more of a nuisance than a problem. Some engines just do it more than others. Most engines that do it will exhibit this problem when they are cold and then it settles down as they warm up.
Is the injection pump an inline or rotary? If it is an inline, it may run an independent oil sump, and you may want to consider changing the oil in the pump.
If still persists and you really want to do something about it, the injection pump will need to go to a diesel shop for service.
HTH - SR

Does this engine smoke? When you check the oil, does it smell like fuel? It may not be a reason to run away from it, but could be a fairly obvious bargaining chip for you to negotiate a lower CASH price. If it runs good, then offer a lesser amount. If he / they won't do it, then consider walking away. Just my thought on the matter. It could be the deal of a lifetime or a basket case worth dodging. It is all going to be based on current condition / value then subtract the perceived repair cost to better consider if it is worth getting into. If it is a GASOLINE engine, they are not that valuable.

 

[SkidRoe]

Pulsing idle is usually something to do with the governor in the injection pump. It is more of a nuisance than a problem. Some engines just do it more than others. Most engines that do it will exhibit this problem when they are cold and then it settles down as they warm up.
Is the injection pump an inline or rotary? If it is an inline, it may run an independent oil sump, and you may want to consider changing the oil in the pump.
If still persists and you really want to do something about it, the injection pump will need to go to a diesel shop for service.
HTH - SR

Done some more thinking on this. If diving into the fuel system, may want to get the injectors checked out first before pulling the pump. Should be done along with any pump work anyway. Just a thought. Cheers - SR

 

[Tazza]

Done some more thinking on this. If diving into the fuel system, may want to get the injectors checked out first before pulling the pump. Should be done along with any pump work anyway. Just a thought. Cheers - SR

I was thinking possible injector issue too.

 

[mmsllc]

I was thinking possible injector issue too.

Basically, the fuel injection pump, hard line to the pump or the injector(s) can cause an imbalance in the engine if one (or more) are restrictive, or otherwise not firing when it should. It'd be best to have all of the injectors removed for bench testing and rebuilding, if need be.