PRM Gearbox Oil Change

[Bide Your Time]

Hi, all.

 

I'm new to the forum, and have looked for my answers elswhere. Apologies if I've missed them.

 

We have a PRM 150 gearbox, and Im about to change the oil. The handbook is of little use, and the gearbox fairly hard to get at, requiring the drainplug to be felt rather than seen.

 

Are there any diagrams or photos around to identify the beast!

[alan_fincher]

You don't have to drain them through the drain plugs.

 

A simple suction pump can go down the dipstick hole, so you can "syringe" out from above.

 

Far easier, and far less mess.

 

Link to example pump

 

Read the PRM manual about checking oil levels, which should be done after it has been running, (to ensure external oil cooler is full), rather than after it has stood not running.

[Bide Your Time]

Wow, that was quick!

 

And a good idea too.

 

Thanks Alan!

[RobinJ]

I'm new to the forum, and have looked for my answers elswhere. Apologies if I've missed them.

 

We have a PRM 150 gearbox, and Im about to change the oil. The handbook is of little use, and the gearbox fairly hard to get at, requiring the drainplug to be felt rather than seen.

 

Are there any diagrams or photos around to identify the beast!

Have a look here:-

PRM 150

Edited November 12, 2009 by RobinJ

[Proper Job]

Or you can get one for half the price:

 

Suction gun

[Chris-B]

2 points to make :

If using a vacuum type pump, run the engine in gear for half an hour or so first to warm up the oil, it makes it easier to remove

 

When refilling preferably use an API CC or CD rated multigrade oil 10/40w is ideal, don't be tempted to use a higher grade (CF/CG) as this will be detrimental to the internal workings

 

Rgds

Chris

[alan_fincher]

Or you can get one for half the price:

 

Suction gun

Your maths is perhaps not spot on (), but it's a fair point.

 

However, I have one of each type, and think the brass one is better because.....

 

1) It pumps in one end, and out the other, so you can pump straight into another container, for only the one set of drips when you finally finish. The syringe type means you have to remove for each "suck" you make, and inevitably (for me at least) make more mess.

 

2) The brass pump comes with a selection of pipes, one of which will even go down the dipstick hole on my BMC, and, used carefully, gets more out of the sump than the brass pump permanently part of the engine marinisation.

[Tony Brooks]

You don't have to drain them through the drain plugs.

 

A simple suction pump can go down the dipstick hole, so you can "syringe" out from above.

 

Far easier, and far less mess.

 

Link to example pump

 

Read the PRM manual about checking oil levels, which should be done after it has been running, (to ensure external oil cooler is full), rather than after it has stood not running.

 

 

When I was on a PRM course we were specifically warned not to do that because there is a ledge inside the box that prevents you getting to the bottom. They were very specific that the boxes should be drained via the drain plug.

 

I have not stripped a modern PRM so can not confirm what we were told.

[alan_fincher]

When refilling preferably use an API CC or CD rated multigrade oil 10/40w is ideal, don't be tempted to use a higher grade (CF/CG) as this will be detrimental to the internal workings

Interestingly Chris, that's not what PRM told me when I contacted them.

 

They are very unfussy about what to use, and say any oil that is suitable for a boat diesel can be used in the box. Because I had acquired some API-CF stuff that I did not want to use in my engine, I specifically asked them, and they said it was perfectly OK to use.

 

It's mostly gone now, so if their advice was wrong, it's too late!

 

When I was on a PRM course we were specifically warned not to do that because there is a ledge inside the box that prevents you getting to the bottom. They were very specific that the boxes should be drained via the drain plug.

 

I have not stripped a modern PRM so can not confirm what we were told.

Interesting Tony - I must admit I do have multiple attempts from several angles, as it is possible to end up with it not on the bottom. Last time I put it into a plastic milk bottle, and managed to convince myself that I had managed to get out close on what the manual says it holds, (Delta box).

 

I certainly can't manage that with my BMC, whether using it's "Calcutt pump", or trying with the dipstick one. I'm more or less resigned on that that I could be leaving as much of a pint of old oil in there, but as I believe they don't all have the same shaped sump, and mine has a few dents in, I suppose it may just be that mine actually holds less than the book figure.

[nb Innisfree]

Prob best to use both, pump for removing most then drainplug for the remaining bit, less messy

[WotEver]

Prob best to use both, pump for removing most then drainplug for the remaining bit, less messy

Which brings us back to the OP - where's the plug?

[journeyperson]

Prob best to use both, pump for removing most then drainplug for the remaining bit, less messy

 

That's a good idea. I use one of those brass pumps for my engine sump but I didn't think to use it on the Delta gearbox. I put the biggest container I could fit under the drain plug (and still get out full) and tried to empty it in stages, sticking the drain plug back in when the container was nearly full. I got in a right mess but was surprised how easily I was able to mop up all the spilt oil with rags and nappies. I'll use the pump next time though to get most of the oil out. I used cc 20w/50 btw, same as in the engine.

[RobinJ]

Interestingly Chris, that's not what PRM told me when I contacted them.

They are very unfussy about what to use, and say any oil that is suitable for a boat diesel can be used in the box. Because I had acquired some API-CF stuff that I did not want to use in my engine, I specifically asked them, and they said it was perfectly OK to use.

It's mostly gone now, so if their advice was wrong, it's too late!

If the CF oil contains any additives that reduce friction etc., there is a danger that the clutches can start slipping prematurely under heavy load, especially if the box gets hot!

Under normal circumstances it shouldn't make any difference, but with an old box I'd probably not risk it?

[nb Innisfree]

Which brings us back to the OP - where's the plug?

 

Underneath at the rear, it is on mine anyway.

 

I actually fitted an adaptor into our PRM drain plug and installed a brass pump which was great to use but kept getting constant leaks from adaptor so in the end I took it off and reverted to the drainplug, shame really but for once or twice a year it's not too bad a job.

[Keeping Up]

If the CF oil contains any additives that reduce friction etc., there is a danger that the clutches can start slipping prematurely under heavy load, especially if the box gets hot!

Under normal circumstances it shouldn't make any difference, but with an old box I'd probably not risk it?

They told me also that any oil suitable for the engine owould be suitable for the gearbox (PRM150)

[Lesd]

Our Shire engine / PRM 260 gearbox came with two brass pumps already fitted, I obviously use them when oil changing and never touch drain plugs. Seems odd that they are fitted like that if PRM recommend using drain plugs because of the shelf Tony mentions.

[Big COL]

Our Shire engine / PRM 260 gearbox came with two brass pumps already fitted, I obviously use them when oil changing and never touch drain plugs. Seems odd that they are fitted like that if PRM recommend using drain plugs because of the shelf Tony mentions.

 

Thats probably because when you fit a pump to any sump, engine or gear box an adaptor is used screwing into the hole where the drain plug has come from. Which should be at the lowest point in the sump allowing you to evacuate all of the oil. Shimples

Edited November 12, 2009 by Big COL

[nb Innisfree]

Our Shire engine / PRM 260 gearbox came with two brass pumps already fitted, I obviously use them when oil changing and never touch drain plugs. Seems odd that they are fitted like that if PRM recommend using drain plugs because of the shelf Tony mentions.

 

Brass pump inlet is probably screwed in place of sump plug anyway so makes no difference to draining.

 

Edited to add BigCOL beat me to it

Edited November 12, 2009 by nb Innisfree

[Lesd]

Thats probably because when you fit a pump to any sump, engine or gear box an adaptor is used screwing into the hole where the drain plug has come from. Which should be at the lowest point in the sump allowing you to evacuate all of the oil. Shimples

 

That makes sense Col, thanks for clarifying. Have just re-read Tony and Alan's posts and they were talking about pumps being fed into the dip stick opening rather than the permanently fitted type.

[alan_fincher]

If the CF oil contains any additives that reduce friction etc., there is a danger that the clutches can start slipping prematurely under heavy load, especially if the box gets hot!

Under normal circumstances it shouldn't make any difference, but with an old box I'd probably not risk it?

I accept what you and Chris are saying, but I thought PRM were pretty highly regarded, so if you can't trust their answer to a direct technical question, it would be a bit worrying.

 

Certainly the PRM manuals I've seen refer to grade of the oil but make no reference to any API spec, so even for a box that were still under warranty it would appear completely OK to use a non obsoleted API specced oil beyond 'CC' or 'CD'.

[Big COL]

That makes sense Col, thanks for clarifying. Have just re-read Tony and Alan's posts and they were talking about pumps being fed into the dip stick opening rather than the permanently fitted type.

 

I am not sure if they are still currently used but there was a system that the auto trade used that vacuumed the oil out via the dip tube. The hand type were mainly aimed at the DIY market as the position of drain plugs were b------s to get to.

[Bide Your Time]

Or you can get one for half the price:

 

Suction gun

 

Ah well, already sent for the one Alan suggested.

 

If I can get under the 'box and drain as well, then that seems a good idea, although I can't imagine a little bit of old oil will matter too much.

 

I intend to use some oil left from the engine oil change done earlier this year. It's mineral 15w/40 from Autherly hire marina. I've gone for semi synthetic in the motor this time.

 

It does seem odd, that the Beta Kubota attached to the said 'box has been well thought out and has a pump installed. Surely PRM know how inaccessable the thing will be when installed, and maybe should do likewise.

 

The boat's on blocks at the mo. Is it safe to run the engine in gear with no load on the prop?

 

Thanks everyone for your help.

 

I'm bound to come up with more queries during my first winter's fettling. Nice to know you guys are there to share your experiences.

[Keeping Up]

If I can get under the 'box and drain as well, then that seems a good idea, although I can't imagine a little bit of old oil will matter too much.

It's the bit at the bottom that holds all the lumps of metal that have fallen off the gears

[Bide Your Time]

It's the bit at the bottom that holds all the lumps of metal that have fallen off the gears

Valid point!

[Canalfreak]

It's the bit at the bottom that holds all the lumps of metal that have fallen off the gears

 

For what it is (or isn't) worth, I was advised to use a Pela pump with the insert going into the dipstick tube so that it reaches the bottom.

 

Then, after that, to remove the drain bung which is apparently magnetic. So you not only can extract the remains of the old oil, but also all the swarf which has adhered to the magnetic bung.

 

Except that "bung" is probably the wrong word.

 

 

Bob.