Yanmar Wiring Harness Concerns

[Kenomac]

The placement of the wiring harness on our Yanmar 4JH3-HTE Turbo diesel has always been a concern for me, it just seems like it's hanging there waiting for something to go wrong. Vibration, moisture, oil.

Should I be worried? Is there something I can do to better protect it from the elements swirling around inside the engine compartment and vibration?

Ken

[NoTies]

The main problem with Yanmar harnesses are the multi plugs. I disconnect them, spray moisture repellant, reconnect and spray with soft seal then support both sides of the join with cable ties. Why don't marine engine manufacturers use tinned wire in their harnesses?

[Badsanta]

Yeah, you pay good money for them. You would think it'd be better quality. not like it's being exposed to heat vibration and moisture.

[Kenomac]

Do you recommendations for the "soft seal" and "moisture repellent?"

Thanks

[NoTies]

CRC 5.56 and CRC soft seal is what I use. I;m guessing you have the CRC range of products where you are.

[Kenomac]

Thanks, I'll check the local stores on Monday.

[lockie]

I rewired my 2GM and did away with the plugs in the engine bay. They are a very weak link in the conductivity chain and are only required for moving the wiring out of the way for heavy work, or removing the engine. For that, it's quite easy to just disconnect at the various termination points (sensors, starter, alternator).

This will only be necessary very rarely, so I am quite happy with my plugless wiring. A bonus is that it is tinned, which the original was not.

Cheers, Graeme

[Kenomac]

At least for a temporary fix, is there something I should wrap these things with? Maybe that plastic black flex hose that's sliced down one side?

[boeing1]

I clamp and secure wiring to keep from vibration, as I would on a aircraft engine. also use good marine wire and connector, not worth to skimp on this

[exMaggieDrum]

Since you have the plugs I would not recommend taping them up and trying to seal them. That is hard to do 100% (although possible). If moisture gets in there it will not dry out and lead to corrosion problems.

The plugs can be an issue - get loose and cause connectivity problems for one or more circuits or corrode. They mostly work though and the way they are made I have found them not to loosen completely. I would wire tie them to the engine or brackets as close to the plugs on both sides. That will help with vibration issues as much as possible.

If you don't have any obvious problems I would leave them be as it would be a lot of work to cut the connectors off and then put together a lot of butt connectors or a bus to connect them all with two extra connectors on each side and screws which can loosen by vibration themselves. The spraying is a good idea in any case.

[TacomaSailor]

We have a Yanmar 4JH-2E that has been well used during the last 22-years. We purchased the boat new in February 1995. The motor has 2,900 hours on it and the boat has spent four years in the very hot Sea of Cortez .

I recently took all the plugs apart to look for corrosion or loose connections.

Every connector was tight and clean. Every pin/socket was spotlessly clean with not a sign of corrosion. They looked like new.

That was the FIRST time in 22-years the plugs have been opened.

I also removed the Type B instrument panel and checked all the connections there. They were also perfect.

The only corrosion I've found in electrical connections associated with the Yanmar is on the starter/solenoid. Our anti-siphon valve as installed at the factory was cheap and leaky. It was positioned directly above the starter and dripped saltwater on it. I replaced that valve after the first year but the corrosion effects continued.

Eventually I replaced the starter and solenoid and now, after two more years, they look like new.

[seabreez]

Originally Posted by NoTies

The main problem with Yanmar harnesses are the multi plugs. I disconnect them, spray moisture repellant, reconnect and spray with soft seal then support both sides of the join with cable ties. Why don't marine engine manufacturers use tinned wire in their harnesses?

The multiplugs used in the marine environment are Wheatherpak connectors and are designed and built to very high standards against very stringent conditions of high salts and moisture cold and hot. These Weatherpak connectors started appearing in the automotive industry around 1975 or so as it was a big problem in the northern countries like Canada where salts is a common road desalinating compound and that also the voltage was varying and decreasing for the onboard computers and sensors and activators. I would not use any softeners for the seals as some of the chemicals conduct electrical currents and might alter readings of sensors. THEN try and find the problem... I worked on onboard computers for fuel injection and and most of the time we had a difficult situation or problem it was caused by the customer that (thaught) he was helping to prevent problems... These weatherpak connectors are working for you and protecting your investment... don't try and take over their job... it does pay!

[NoTies]

In my experience the ones on Yanmar are crap. There is also on Yanmar an additional wire for the start relay which is a simple bullet connector in addition to the multiplugs.