Coolant “filling neck” 4JH4E yanmar......

[NYSail]

Hello all!

So yanmar 4JH4E has a pressed on filling neck for coolant. Have heard these are an issue and guess what I am starting to have a slight leak around where the “fill neck” is set. Rather than pull dismantle everything has anybody tried using a sealant around the seam?? Would obviously have to be able to withstand the heat and pressure.... not looking for a duct-tape repair, however if I can fix this successfully otherwise I would rather do so. So far minimal loss of coolant and no overheating issues.

Thanks
Greg

 

[kappykaplan]

JB Weld was used on my coolant neck.

 

[NYSail]

JB Weld was used on my coolant neck.

I was thinking the same....... Thanks. Think I will give it a try.

 

[kappykaplan]

@NYSail , what was the final resolution to this? Tks.

 

[NYSail]

So I put the jb weld on the base of the neck.... went out for the weekend and when I go to my destination checked and there was still a leak.Turns out there is a small drip coming from the cap..... Cap is brand new this summer. I am going to remove the cap and drain a bit and inspect everything.... seems strange.

 

[kappykaplan]

If there's a divot on top where the cap gasket meets the neck, you can use JB Weld to fill in the divot. Been there, done that, too.

 

[ggrizzard]

There are "factory" caps and there are "after market" caps
and then there are defective caps of both kinds.
Some have reported that some "after market" caps don't seal properly.
Others have said that some "factory" caps were defective.
You may have to do the "trial" and try again method of solving your problem.

 

[Calif. Ted]

When I bought my boat there was an aftermarket cap and a small leak which I also thought came from the neck, tried a couple caps with same result. Found the original cap in the nav. desk and when installed no more leak. Close inspection revealed the gasket was slightly larger diameter than off brands. Yanmars are VERY particular about the cap.

 

[NYSail]

Bought brand new yanmar cap.... am going to inspect today and see if there are
Any visible deformities.

 

[NYSail]

So think I found my answer.... pulled the cap
and inspected the rubber and also the fill neck. Cap appeared to be seating properly and all seemed good. However pulled
manual and was reading that the recovery tank should be same height or no more than 11 inches above the engine. Mine was about 12.5. Never crossed my mind..... assumed pressure would be adequate to push fluid to tank. Anyway I lowered it about 4 inches and after a hard run out then back into harbor no signs of coolant. Keeping my fingers crossed.

Greg