Yanmar 4jh4-hte

[Svbluemoon]

I have a yanmar 4 JH4-HTE. Has run beautifully but currently when accelerating above 2700 RPMs really starts smoking black smoke so much that you can see fuel in the exhaust water. Any idea of what needs to be fixed or adjusted

 

[Mistroma]

Black smoke means too much fuel and not enough air. I have the 4JH4AE which is the non-turbo version and it doesn't have an air filter. If yours is the same then that rules out a badly choked filter. I imagine that the turbo would be a candidate, especially as it is smoking badly at higher revs. I think that your engine also has an exhaust gas re-circulation valve which could also cause problems but not 100% certain. I can check the service manual later.

I would imagine that injector faults would develop more slowly and usually not all at once across 4 injectors. Sorry not to be able to say it's almost certainly X and a well known problem.

UPDATE:
I had a quick look at the Service Manual and it does show an air filter on the HTE model and also mentions cleaning the turbo every 250 hours (there's a section showing the flushing process). It also showed a diagram relating to mixing into intake and I assume that will be the exhaust gas re-circilating part.

It is on my web-site if it is of any use, along with the Operation Manual.

Service Manual
Operation Manual

 

[Jim@sea]

I bought a boat with one of these engines, I believe that the impeller is really difficult to swap, on the bought I bought it had a service 50 hours before, but the mechanic had just put that the impeller was in good condition. (it wasn't) thinking that a marine mechanic would not pass up the opportunity to sell an expensive impeller, I had a mechanic remove the pump to get at the impeller and it was badly disintegrating.

 

[Mistroma]

I bought a boat with one of these engines, I believe that the impeller is really difficult to swap, on the bought I bought it had a service 50 hours before, but the mechanic had just put that the impeller was in good condition. (it wasn't) thinking that a marine mechanic would not pass up the opportunity to sell an expensive impeller, I had a mechanic remove the pump to get at the impeller and it was badly disintegrating.

I wasn't aware that this was a problem with this engine as it seems to be similar to my non-turbo version. Perhaps Yanmar stuck something in the way of the raw water pump or moved it without updating the service manual. Glad I have the non-turbo version.

It is a piece of cake to change on the 4JH4AE model though I did make a DIY tool for about £2 make it even easier. It only works with the threaded impellers as it screws into the end. DIY Yanmar 4JH4AE Impeller Puller

 

[rotrax]

I have just given my 4JH4-HTE Yanmar its 1000 hour service. The recommended impeller change is 1000 hours.

As the heat exchanger, intercooler and turbo require servicing at this interval the impeller was easy to do with these parts removed for service. I removed the alternator too. The impeller was in good condition when removed considering its long service. Three small corners of the blades were found in the intercooler.

There is only a gauze on the intake but thus can get contaminated during heavy engine use by the breather pipe from the rocker cover. I inspect mine frequently and clean if required.

It might be worth inspecting the exhaust elbow.

Yanmar really should make such an important service part easier to change. Not impossible at sea, but very difficult.