Attention Gearheads: Yanmar Question

[Rick D]

On a recent trip, I noticed my oil pressure on my 4jh went through the floor at idle. After some research, I purchased a mechanical guage. It checked out 30 pounds higher (40 LBS) at the same idle. I then grounded the lead wire and the guage went to 80+ pounds. So, it must be the sending unit. I took the sending unit and manifold off and cleaned/checked them. (The manifold is basically a 90 degree brass fitting.) I went to my Yanmar guy who almost fell over at the $180 replacement cost which didn't make me too happy either. Especially since this is the third one. The first was dead when I got the boat 1000 hours ago. The replacement was dead out of the box. This is the third. Needless to say, I'm having a rough time spending $180 for a sending unit. My diesel guy had a generic one which he sold me for $35 but it has incompatible threads (metic vs. SAE?) And, adaptors are not to be found. Soooo... I went to a wrecking yard and the guy found a beat up one on some Japanese truck engine. It fit the manifold, and shows about the correct oil pressure at idle but then it falls when I rev it, so that unit isn't good either, and it jerks it's way around, but it did prove the point that the original sending unit is indeed failing. As a somewhat humorous aside, I drove by a VW place and checked with their parts dept. They had one for a Rabbit that even looked similar in the diagram... but for $180 too. Anyhow, I'm getting to my question. I looked at the Yanmar unit, but it is devoid of identifying stampings, so cross-referencing is out. I certainly can't imagine they make a custom sending unit, so it must be from a large supplier. What would your next step be? I can easily just buy another Yanmar unit at this point, but I sure hate to pony up the money for a part that ought to cost $45 and has failed before. Advice welcomed. Rick D.

 

[Miles]

You might try this...

Hi Rick,You might try this site: www.egauges.comI got a water temp sending unit from them to put on my Yanmar and was very happy with the service. They have lots of gauges but more importantly for your needs a wide assortment of sending units and bushings. I bet you could put something together for a lot less than $180. Your threads might be metric or maybe BSP instead of NPT but you can probably get a bushing to take care of that. I think senders are pretty much compatable as long as you match Ohms and temp. or pressure range. Good luck!

 

[Ross]

Go to a Yanmar tractor dealer

and see if he has one. I'll bet good money that any metric sending unit will work.

 

[Landsend]

There is a difference...

The oil pressure sending unit for a idiot light is a simple spring switch. That is either open or closed to make the lamp go out according to the oil pressure being present or not. Such as running the engine at rpm or the engine off.The oil pressure sending unit for a gauge is a varible resistor with a membrane or moving part that changes resistance according to the force exerted on it. Thus moving the needle on the gauge.Why don't you install a totally mechanical gauge that doesn't require a sender? Also NAPA auto parts have all the fittings needed in both SAE and Meteric.Good luck.

 

[Rick D]

Some good thoughts, guys: keep them coming...

Landsend: it isn't the idiot light pressure switch; it is the guage sending unit. Tried a couple of auto parts stores and zero luck for adaptors. Did not try a NAPA tho. I will. The accessory units I saw in the stores were 100 LB and the Yanmar and generic diesel are 80 LB. Ross, the only thing I could find on-line for Yanmar tractors in 4 cylinder configurations were pressure switches. Miles: I must have missed eguages. I'll take a look. Thanks for all your help guys. Any more suggestions? Rick D.

 

[Calif. Ted]

Rick, I've attached a page from the Stewart-Warner

catalog with their pressure sending units, note part #279A, 80 Lbs. Gotta be one tenth of the official price if it will work, there's a little guide to choosing a sender that may be helpful on this page also. http://www.stewartwarner.com/Catalog/sdrpress.html#prst

 

[Clay]

Metric = In dutch it means make it work

I'd have to agree with #2 Ross, I'd make the $35.00 replacement work.My first attempt would be to rethread it to SAE.

 

[RAD]

Rick,

Just went thru the same kind of stuff with my electric temp gauge on my ODay with a Westerbeke engine,ended up installing a mechanical gauge and it works well and I'm thinking of replacing the electric oil gauge with a mechanical gauge for the same reason

 

[Steve Dion]

adaptor

Rick:Just go to a hydraulics shop and have them make up a hose with the two fittings. BPT on the one end and the SAE fitting on the other. There is no need to worry about finding the correct part. I think you can also re-tap the BPT end to make it fit a SAE fitting, but this is not my idea of a good thing to do.

 

[Calif. Ted]

Steve's reply reminded me of Earls Performance

Plumbing, now a division of Holley, we used to have all kinds of custom braided lines etc. made up by them. They started as Aircraft plumbing and expanded into the auto market, they do have some Metric adapters.

 

[Rick Webb]

NAPA

NAPA has all the fittings you'll need and the sending units. A dock mate just went through the exact same senario. A machine shop can make a manifold for you with the threads you want on either end. He ended up making a tee and keeping the mechanical gauge in the engine compartment as he no longer trusted the electrical one completely.

 

[Rick D]

Thanks Again, Guys...

All good suggestions. I'll make a trip to NAPA and there is a custom hose outfit right on the way. Something will work. Rick D.

 

[Fred Ficarra]

And thanks Ted for the Earl's link.

We plan to replace all of the fuel hose on my Camaro with Earl's stuff this winter.

 

[John Nantz]

Fittings on Diesel Engines

A word of caution about hanging stuff via Tee-ing on a diesel engine with, say, a brass fitting. A diesel shakes much more than a gas engine and, over time, can cause fatigue to brass fittings that have a weight hanging out on them. Good practice is to have the shortest possible distance between the weighted object and the block.The oil sending unit on our 3GM30 has a very small thread (the details are in my shop manual on the boat) and Tee-ing off to attach, say, a sending unit was not an option I was willing to take because over time the brass fitting could fail due to fatigue.The route I took was to use a VDO dual-sender which had two connections, one for the idiot light/beeper and the other for the gauge. The installed clearance is "just" clear of the V-belt for the alternator. Threads: this has been so long ago I don't remember the details but I do remember the long drawn-out problem trying to match thread types. I "think" what I ended up with was a VDO sender that had a brass thread that closely matched the Yanmar cast iron thread and I just tightened it real tight. This was per a respected parts/mechanic specialist recommendation. Setpoint: The other part of the issue was finding a sender that had a set point that matched the Yanmar oil pressure alarm on and off settings. The VDO sender was close and I opted for a setpoint below the Yanmar setpoint to "err on the side of the angles". The annoying part of theis option is the alarm goes off a tad quickly and turns off a tad slowly so I get to listen to the shrill "beep" a little more than I'd like. The solution to help mitigate this when turning the engine off is to be ready to turn the key off as soon as the engine stops.Hope this help too.

 

[Fred Ficarra]

John,

That threaded oil pressure fitting is 1/8 inch pipe. That's why and how you had to thread it in, until tight. For the annoying buzzer at shut-down, I just turn the key off first. Hey, great day huh? What are we doing on-line? The boats waiting. I'm outta here!

 

[Rick D]

Fred and John: Couple of Q's

John: the VDO type sensors are 10-180 Ohms and the 'other' are 240-33 Ohms. I assume we are talking two different standards here. I would further assume most Japanese engine manufacturers would settle on a standard and install one or the other. Any idea which Yanmar is? Fred: my 'generic' replacement sensor (sending unit) is 1/8 NPT but does not fit the manifold. The OD looks about the same, so I'm assuming the OEM is metric. The used one from a Japanese gas engine fit perfectly, so I think it's metric, altho my Yanmar guy said not all the fittings are metric. Sigh... anyone else want to weigh in? It'll be a week before I get down to the parts houses. Believe me, once I solve this, I will post the results because I know it's a problem with other 4JH owners. It's getting tempting to just buy another sensor, but $180 for one that's failed three times already? I'll play around with this some more.... Rick D.

 

[Fred Ficarra]

Sorry to hear about your metric thread Rick.

Wish I could suggest something. *o

 

[Ross]

Check with the mechanics at the

Yanmar, Kabota dealers or at least talk to the parts man. these started life as industrial engines that have been marinized. Buy the marine parts from the marine engine dealer and the rest from the tractor dealers.

 

[Rick Webb]

Using a Tee

What my buddy did was use a flexible line to the block and mounted the sending unit and a mechanical gauge to somthing else I can't remember now what it was on . The threads are not metric they are a British standard I forget what it is called right now as well. It is a little early and I am not hitting on all eight yet.I'll ask him what exactly he did and let you know.

 

[Rick D]

British Standard?

Heck, I ought to go and take one off my old Jaguar! Oops, just remembered I replaced it and it was more than the Yanmar... Oh well *grr