Testing Oil Pump on PRM Gearbox

You can't split the Gearbox from the flywheel cover until the cover is off, it's bolted on the inside. If you take off the rectangular top plate and turn the engine you will see if any parts of the gearbox are rotating. If so the drive plate is OK, and suspect the oil pump, if not then the drive plate has sheared or splines gone.

It also looks like your engine mounts are on the flywheel cover, so you will need to prop the engine up as well, wood blocks and wedges under the sump?
 
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fisherman said:
You can't split the Gearbox from the flywheel cover until the cover is off, it's bolted on the inside. If you take off the rectangular top plate and turn the engine you will see if any parts of the gearbox are rotating. If so the drive plate is OK, and suspect the oil pump, if not then the drive plate has sheared or splines gone.

It also looks like your engine mounts are on the flywheel cover, so you will need to prop the engine up as well, wood blocks and wedges under the sump?
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Thank you Fisherman. Just a quick question, when you say turn the engine, do you mean start the engine and look inside the inspection plate. Also is the inspection plate the rectangle plate that the hydraulic hoses attach to.

Trying to get a confirmation of the actual gearbox so I can get a manual, managed to get one for the 2.2 bmc engine, but it's also looking hard to find another oil pump, but have seen a second gearbox a prm 160 which I believe is the older version of the one I might have.

Thanks for your time
 
Fisherman must be fishing....
turn the engine over on the starter, but with the stop cable pulled (if you have one) so it will not start. No big deal if it does start, just oil sprayed everywhere.
The inspection plate is the one without the hydraulic hoses going to it.
Have a look here for your gearbox-
http://www.prm-marine.com/shop.php?sec=cat&cat=1
 
Hi all.

Have managed to go down to the boat this weekend and found where the inpection plate was to view what I think was the drive plate.

My first thought was that the large teethed spindle (drive plate I believe) was completly dry, with no oil. I turned the engine over and no oil came out but the large fly wheel was spinning at speed.

I tested again putting the engine in gear, and the spindle was turning, slower speed seemed a little wobbly, but still no turning at the rear where the prop shaft would connect.

I think it must be the oil pump, but would the same pump also oil the drive plate as couldnt find anywhere to add oil in this area.

Thanks for all your help and any sources for getting a new / reconditioned oil pump for prm 100 gearbox

Cheers
 
Are you looking in the gearbox or the engine flywheel cover? The drive plate is attached to the engine flywheel, the shaft on the front of the gear box fits in it. There should be no oil on the drive plate. You still need to remove the rectangular plate on top of the gearbox to see if the drive is getting as far as the gearbox forward end input shaft, if so the drive plate is OK. This decides whether the gearbox has to come off.
The drive plate is a large diameter plate bolted to the flywheel, it has a smaller circular plate in the centre which has a plastic 'spider web' between it and the flywheel. The smaller plate has the gearbox toothed spindle in its centre, the large plate drives the plastic which drives the small plate which drives the gearbox. The plastic is designed to fail under shock overload, such as a fouled prop.
 
fisherman said:
Are you looking in the gearbox or the engine flywheel cover? The drive plate is attached to the engine flywheel, the shaft on the front of the gear box fits in it. There should be no oil on the drive plate. You still need to remove the rectangular plate on top of the gearbox to see if the drive is getting as far as the gearbox forward end input shaft, if so the drive plate is OK. This decides whether the gearbox has to come off.
The drive plate is a large diameter plate bolted to the flywheel, it has a smaller circular plate in the centre which has a plastic 'spider web' between it and the flywheel. The smaller plate has the gearbox toothed spindle in its centre, the large plate drives the plastic which drives the small plate which drives the gearbox. The plastic is designed to fail under shock overload, such as a fouled prop.
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Thank you Fisherman, was looking at the wrong inspection plate. Will check the rectangle plate on my next visit. I know from viewing via the Dipstick hole that there was nothing turning inside. If its the plastic spider web that has failed under shock, which to me sounds right, can these be purchased seperately or do you need a complete plate.

Thanks again
 
You get the drive plate as a complete assembly.
Its quite common for the spline in the centre to have stripped when you lose all drive, the plastic 'spring' is designed to fail safe.
 
On my last visit to the boat, I could see that the gear box cogs were not turning via the inspection plate, so now need to remove gearbox in order to check / replace drive plate.

Will need to jack up engine as Fisherman pointed out that the flywheel cover is on the engine mounts, so this will be fun.

First problem that I had was trying to push prop shaft back a few inches. It turns freely and I have removed from coupling but whats the best way to pull out. There are a number of bolts at propellar end which I believe keep the proellar in alignment via a metal block that goes through the boat, but not sure if I need to also undo these, or is it simple a case of a bit of brute force pulling.prop 2.jpg

Slowly getting there, but the weather is to nice to work so chilling.

Cheers
 
nashynetfit said:
On my last visit to the boat, I could see that the gear box cogs were not turning via the inspection plate, so now need to remove gearbox in order to check / replace drive plate.

Will need to jack up engine as Fisherman pointed out that the flywheel cover is on the engine mounts, so this will be fun.

First problem that I had was trying to push prop shaft back a few inches. It turns freely and I have removed from coupling but whats the best way to pull out. There are a number of bolts at propellar end which I believe keep the proellar in alignment via a metal block that goes through the boat, but not sure if I need to also undo these, or is it simple a case of a bit of brute force pulling.View attachment 33537

Slowly getting there, but the weather is to nice to work so chilling.

Cheers
Click to expand...

Don't undo any bolts on the outside, just rotate the prop and pull by hand, it should come back easily. The PRM box is quite heavy, useful if you can get a rope tackle above it, take the bolts out starting at the bottom leave the top two until you have taken the weight of the box, it has to slide back about 4in to pull the splined shaft clear of the drive plate.
 
fisherman said:
Don't undo any bolts on the outside, just rotate the prop and pull by hand, it should come back easily. The PRM box is quite heavy, useful if you can get a rope tackle above it, take the bolts out starting at the bottom leave the top two until you have taken the weight of the box, it has to slide back about 4in to pull the splined shaft clear of the drive plate.
Click to expand...

Thank you fisherman, managed to get prop shaft back and rope up the gear box and lift engine a little.

Problem I had yesterday is that even though every bolt was removed around the gearbox and also engine mount bolts, there was no movement in the gearbox, not even a line to crack the paint.

I was thinking of putting the engine mount bolts back into the gear box and tapping hear with a hammer.

Any idea what I could be doing wrong. Will try and just jack up the gearbox as this may separate.

Thanks for your time.
 
Don't tap. The flywheel housing is probably cast ally by the look of it, and the total weight will have too much inertia to have an effect unless you sledge hammer it which would be fatal.. There are dowels round about the feet, where it looks like a bolt might be but there isn't one, these will be hanging on. Take the weight of the engine separately, then being sure that all the bolts are out except the top one or two, just relax these a couple of turns, lower and raise the gearbox with a rope tackle, move it side to side gently with a bit of wood levering the back end, try levering the feet backwards alternately, it will go!
 
Looking at the pic again I can't quite tell if there are dowels or bolts by the feet: in any case the flywheel housing has a male register which is a snug fit into the female on the engine block. Just wiggle the box back and forth, and as you suggest jack up the back end to open up the joint at the bottom, then let it drop gently to open up the top.
 
fisherman said:
Looking at the pic again I can't quite tell if there are dowels or bolts by the feet: in any case the flywheel housing has a male register which is a snug fit into the female on the engine block. Just wiggle the box back and forth, and as you suggest jack up the back end to open up the joint at the bottom, then let it drop gently to open up the top.
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Thanks Fisherman,

Finally got it off after 2 hous off wiggling, swearing and sweat. I have taken a picture of the centre of the plate as can see some damage hear, buts its not as bad as what I thought, the spindle on the gear box also has a small amount of wear, about 2 mm, but would have thought that there would have been some lock in place. Couldn't see any plastic bits though.

Many thanks for your help, no way I ould have done this just trying to read a manual and it would have cost a fortune to pay a mechanic as its such a tight spacce to work in.

drive plate.jpg
 
Well done.
That type of drive plate has got steel springs instead of the plastic ones we expected... however its hard to be sure from the photo but it looks like the spline is only engaged with the shaft for the first 1/4 inch?
The splined shaft should engage with the drive plate by at least an inch. (edit- but not bottom out against the centre of the flywheel)
Measure the depth of the spline, and compare the length of the gearbox shaft, and you may well find that a spacer is required between the flywheel and the driveplate.
If you remove the five cap screws (''allen head'') you can try the fit of the driveplate on the gearbox input shaft, and see how much slack there is between the two. It should slide easily on the shaft, but very little rotational play, if any.
 
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Well done not the easiest of jobs to do but you do need to sort the length out hope no damage to the gearbox input shaft that will be an expensive part to have to replace and require a gearbox rebuild. when you order the replacement they will be able to sort a spacer out to correct the length problem more money but at least you will have confidence in the set up.
 
Thanks Northup,

This may sound stupid, but as its a forum I'll ask. Would anyone consider putting washers behind the bolts of the allen keys in order to push the spline furthe into the shaft. Was just thinking that by doing this I may be able to get a connection again between the spline and shaft, apart from the first 1/4 inch which is damaged.

Failing that I'll orer a new drive plate, but would this just be the inner part (allen key area) or do I need to measure up the whole drive plate.

Thanks again.
 
Have a look at the R&D marine website
www.randdmarine.com

A drive plate is made up to requirements from three components
Back plate sized by diam and bolt hole size and pattern
Centre section with spline to fit gearbox
Damper determined by torque/
Contact ASAP for supply
 
Hi Nashynetfit

I would be very reluctant to use washers to space out the drive plate part of the security is the friction the clamping force of the plate to the flywheel, in a get you home bodge OK but as a permanent repair would go for a spacer properly made a lot of twisting force on that plate. Have seen your setup before if you check your plate may find just reversing it will position the spline in the correct position would not be the first one to be fitted the wrong way round, but I would still replace the plate for a new one. If you replace, when ordering give dimensions and you will find they will be able to supply a plate with the correct spacing to fit your box, ASAP supplies are as good as any body as is Lancing Marine Good Luck

Steve
 
sneil said:
Hi Nashynetfit

I would be very reluctant to use washers to space out the drive plate part of the security is the friction the clamping force of the plate to the flywheel, in a get you home bodge OK but as a permanent repair would go for a spacer properly made a lot of twisting force on that plate. Have seen your setup before if you check your plate may find just reversing it will position the spline in the correct position would not be the first one to be fitted the wrong way round, but I would still replace the plate for a new one. If you replace, when ordering give dimensions and you will find they will be able to supply a plate with the correct spacing to fit your box, ASAP supplies are as good as any body as is Lancing Marine Good Luck

Steve
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Thanks Steve.

Will replace the plate, just 1 less thing to worry about, but does seem to have been fitted poorl, or a bad design / wrong plate as there is only minimal contact between the two parts.

Trying numerous suppliers now, so hopefully can get what I need soon.

The attached pictures show a bit clearer.Drive Plate 2.jpg

Thanks
 
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