No oil pressure

[DrunkenDonkey]

Good morning all,

 

I have to start off by saying over the 5 years I have had my boat I really have not given it the TLC it deserves. I don't own a car so this has been my only experience with an engine and regular maintenance and servicing etc. has not been the priority it should have been. Now that I am learning a bit more about how engines work and how close to death my poor little T80D (Thornycroft 80D - mitsi base) probably was, I'm trying to get to work fixing it up as much as possible.

 

So... first on the list was to get the oil sorted. I had been using the wrong oil for some time and hadn't changed the filter in the whole time I have had it. Over the past year, the oil pressure gauge has been slowly dying a death. At certain RPM it would show maybe 14-30psi but then a few more or less revs than that perfect sweet spot and it would just drop straight down to 0. More recently, this has become worse until now, where the oil pressure shows constantly 0, no matter what I do.

 

I have finally been able (due to other damage!) get my head right down to the oil filter and could see a fair amount of oil on the engine around the filter, although no obvious damage to the filter itself. I have run 2 engine flushes through the engine (both with new filters) and topped it up to the top of the stick with some more suitable oil. Still no pressure, not a sausage. OK, so now I'm thinking the instrument is faulty and maybe I had an oil pressure fault before due to the old filter, but the gauge has also died on top of that.

 

Next step, check the panel. Lo and behold, the instrument cabling has become loose!! Plugged that back in and...… still nothing at all.

 

Where should I be looking next? Could the sender be faulty and can it get gunked up and need a service itself? Since the oil change the engine is reeeeally purring, so I'm not too worried that the oil pressure is actually 0, it sounds so much healthier and happier since the oil changes. Is there any way to check if the sender is actually working?

 

Thanks in advance.

[Tony Brooks]

Check the large multi-connector that is usually in the main engine to panel wiring harness (maybe two) and if that and the wires are OK clean and tight I would suggest it is almost certainly a faulty sender.

[DrunkenDonkey]

Thanks for the quick response Tony. I love your website by the way, it is part of what has inspired me to get my hands dirty.

 

That was kind of my thoughts, just check all the connections are working as expected. If the sender is faulty, is this a serviceable part? For example, just taking it out and giving it a clean jobby, or if it's dead it's dead and I need a new one?

[WotEver]

1 minute ago, DrunkenDonkey said:

if it's dead it's dead and I need a new one?

This

[DrunkenDonkey]

Thanks WotEver. I presume they are relatively universal and not specific to an engine?

[Tony Brooks]

Regrettably probably specific to gauge depending upon if its built to US or European resistance specification. The, to make matters worse, you need to ensure the sender thread matches the thread in the engine although adaptors are available. Finally it may or may not have an additional terminal for the oil pressure warning lamp and it may or may not ground via the case or a terminal. I have no idea if Throneycroft used the basic Mitsubishi fitment or one they chose but I am sure someone will be along soon who does.

[DrunkenDonkey]

Thanks Tony, some things there I would have likely forgotten to check ?

 

Finding out anything about my engine is a bit of a nightmare. After weeks of searching I managed to get the specs and manual for the base engine, but can't find anything related to the marinized version.

[Tony Brooks]

Another through - make sure the negative to the gauge is OK.

 

My guess would be that it grounds through the case and suspect the thread will be 1/8 NPTF. If there is only one terminal on the sender I suspect you will have a separate oil pressure switch. If two then it is likely one is for the oil pressure switch and if so those can be expensive. If my boat I would probably try to fit a T adaptor plus  a sender and switch.

[DrunkenDonkey]

It has two terminals on the end, I can remember that much from my weekend investigation. But you know what, the negative to the instrument is a good shout. The wiring in my boat is absolutely awful and that is a whole weekend  job (and probably the rest) to get to a point where I feel happy, but I'm sure there are other loose cables behind the panel. In the past, after my head lamp stopped working, I tried to plug things back together and ended up with a very large amount of smoke from the panel, so I have been hesitant to try again.

 

I think the best idea would be to rewire the gauge with new cable and do it outside of the panel to check if I can get it working that way, then worry about getting the loom sorted and the cables nice and tidy

 

I don't have much experience with engines as I'm sure is evident by now! But I'm assuming that if I had an actual oil pressure problem, I wouldn't be getting oil up to the filter (which I am) and it wouldn't have been happily plodding along for months and months without some horrific grinding noises.

[Guest]

28 minutes ago, DrunkenDonkey said:

It has two terminals on the end, I can remember that much from my weekend investigation. But you know what, the negative to the instrument is a good shout. The wiring in my boat is absolutely awful and that is a whole weekend  job (and probably the rest) to get to a point where I feel happy, but I'm sure there are other loose cables behind the panel. In the past, after my head lamp stopped working, I tried to plug things back together and ended up with a very large amount of smoke from the panel, so I have been hesitant to try again.

 

I think the best idea would be to rewire the gauge with new cable and do it outside of the panel to check if I can get it working that way, then worry about getting the loom sorted and the cables nice and tidy

 

I don't have much experience with engines as I'm sure is evident by now! But I'm assuming that if I had an actual oil pressure problem, I wouldn't be getting oil up to the filter (which I am) and it wouldn't have been happily plodding along for months and months without some horrific grinding noises.

These people are very friendly and helpful with Mitsu based marine engines. I have had various items/adaptions for my Mitsu based Vetus from them:
http://cheshiremarine.co.uk/

Thornycroft who built your engine where local to me but now retired. Excellent engine built by an excellent guy. Not sure if they still do spares, but the number I have is  01772 611144

ps this is a rugged base engine designed for generators, forklifts etc and seem to be able to take abuse.

I have just had a problem with a Vetus control panel due to severe condensation, just a thought. Likely the pressure switch though. Worth changing anyway.

Edited January 21, 2019 by Guest

[DrunkenDonkey]

Ta Catweasel, I'll keep them in mind. I tried e-mailing Thornycroft for a manual but had no response, might try giving them a call.

 

The base was a K4D if I have correctly ID'd it now and I have managed to get hold of the spec sheet for that, so most of what I need is in there, but if I want to get more technical it would be really good to get eyes on the T80D manual itself.

 

The condensation thing is a good shout too. I get quite a bit inside the gauge itself.

 

I think I'm just going to have to attack the wiring a bit and see if I can get it any life. The thing that concerned me most is that it was slowly getting worse and worse pressure for a long time, before it started to show 0 constantly. That to me sounds more like an actual pressure issue than faulty sender etc. But hopefully I have had 2 separate problems and the pressure has improved with the filter change and the gauge has it's own fault somewhere.

 

?

[WotEver]

11 minutes ago, DrunkenDonkey said:

The thing that concerned me most is that it was slowly getting worse and worse pressure for a long time, before it started to show 0 constantly. That to me sounds more like an actual pressure issue than faulty sender

Not necessarily. It could be either. Or even the gauge, but hopefully not. 

[Phil Ambrose]

If it helps, the control panel for my type 80 was outside in a metal box with a hinged front lid. I had issues and upon removing the panel I found rain ingress with the multi connector sitting in water. I drilled a suitable drain hole in the base and made sure the back of the box was sealed watertight as it appeared to be just tacked to the rear cabin bulkhead. This sorted the water problem, I then decided to join all the wires with bullet connectors and do away with the multi connector,  this arrangement worked a treat, have never been keen on multi connectors.

Phil

Edited January 21, 2019 by Phil Ambrose

[DrunkenDonkey]

I have the same set up and yes there is absolutely water ingress behind the panel going by the amount of orange in there, however it seemed pretty dry at the mo. I will end up taking the multi connector off first I think and see if it starts working wired up directly to the gauge.

 

The engine cabling is just horrendous at the mo so I'm sure I can't make it too much worse!! :')