Raymarine autohelm type 1 hydraulic pump/drive repair

[daveNZ]

Final note on this autohelm pump. I purged the system with 2litres of new oil (single helm, single ram) bled both sides of the steering ram, closed those and spent ages going from hardover port to starboard, each time forcing helm further to bypass the relief valve. When returning the helm from pressuring the relief valve, more air would come up to the reservoir. This continued for maybe 20 repetitions. I don't think there is any leak, it just took a while.

The autohelm pump.....when reassembling the hydraulic pump I replaced the o-ring which sits in a diamond shaped groove between the pump housing and the gear housing. (Easily seen in the photos). I did use a 3mm whereas the old one was 2mm. I didn't think it would matter as there are 4 cap screws holding these aluminium blocks together; apparently hard against each other. Apparently not!!

While it sounded ok, the gear-pump whirred away but the ram didn't move, so it wasn't pumping oil. I pondered for a while, wondered if there was air trapped in the gears?? Instead of disconnecting the hydraulic lines and taking the pump home, again, the one thing I could do in place was remove the gear housing and inspect the gears. There is a partial scoring of the pump housing, created by the gears running against it, so the clearance is obviously almost zero. The gears are recessed into the gear housing, and I guess the thickness of the gears should be 'slightly' less than the depth of the recess? Anyway, I put the old, thinner, o-ring back in, reassembled and it worked perfectly. I thought the thicker o-ring would have been compressed so as to not hold the housings apart, and therefore not affect the gears' ability to pump oil but obviously not. It is 'possible' that the fastening were not tight enough previously with the thicker o-ring, and didn't fully compress it, but I don't think so. Unfortunately I didn't check that before replacing with the old thinner o-ring, but I am pretty careful tightening things in sequence and firmly.

I'm sure these hydraulic gear pumps are not intended to be serviced, and I haven't tried to get drawings from HyPro Marine to check clearances etc. but I guess if there was a problem one could go as far as resurfacing one or other face of these housing to improve things.

Anyway, lesson is these things are simple and well worth attempting to service if you do your own work elsewhere.
I spent $5 on epoxy glue, many hours and saved NZ$1200 , love it! Thanks again for the helpful comments.


Sent from my iPad using Cruisers Sailing Forum

[deblen]

Originally Posted by daveNZ

Final note on this autohelm pump. I purged the system with 2litres of new oil (single helm, single ram) bled both sides of the steering ram, closed those and spent ages going from hardover port to starboard, each time forcing helm further to bypass the relief valve. When returning the helm from pressuring the relief valve, more air would come up to the reservoir. This continued for maybe 20 repetitions. I don't think there is any leak, it just took a while.

The autohelm pump.....when reassembling the hydraulic pump I replaced the o-ring which sits in a diamond shaped groove between the pump housing and the gear housing. (Easily seen in the photos). I did use a 3mm whereas the old one was 2mm. I didn't think it would matter as there are 4 cap screws holding these aluminium blocks together; apparently hard against each other. Apparently not!!

While it sounded ok, the gear-pump whirred away but the ram didn't move, so it wasn't pumping oil. I pondered for a while, wondered if there was air trapped in the gears?? Instead of disconnecting the hydraulic lines and taking the pump home, again, the one thing I could do in place was remove the gear housing and inspect the gears. There is a partial scoring of the pump housing, created by the gears running against it, so the clearance is obviously almost zero. The gears are recessed into the gear housing, and I guess the thickness of the gears should be 'slightly' less than the depth of the recess? Anyway, I put the old, thinner, o-ring back in, reassembled and it worked perfectly. I thought the thicker o-ring would have been compressed so as to not hold the housings apart, and therefore not affect the gears' ability to pump oil but obviously not. It is 'possible' that the fastening were not tight enough previously with the thicker o-ring, and didn't fully compress it, but I don't think so. Unfortunately I didn't check that before replacing with the old thinner o-ring, but I am pretty careful tightening things in sequence and firmly.

I'm sure these hydraulic gear pumps are not intended to be serviced, and I haven't tried to get drawings from HyPro Marine to check clearances etc. but I guess if there was a problem one could go as far as resurfacing one or other face of these housing to improve things.

Anyway, lesson is these things are simple and well worth attempting to service if you do your own work elsewhere.
I spent $5 on epoxy glue, many hours and saved NZ$1200 , love it! Thanks again for the helpful comments.


Sent from my iPad using Cruisers Sailing Forum

Great job!! You are now the official forum expert on these pumpsets.
Gear & impeller pumps require very tight fit between axial faces of gears/impellers & their housings in order to build & maintain pressure.Basically the ends are "scuffing" the housing,& that is where you see the most wear. The oil or water being pumped "squeezes" into this area & provides the final sealing.
Just as importantly.the fluid being pumped provides the lubrication between the ends of impeller/gears & housing. That is why a rubber impeller is destroyed quickly due to lack of water. Good argument to install a Speedseal kit in RW pumps.
Thanks for the posts.They will be an excellent reference in future.
Cheers/Len

[daveNZ]

Thanks Len, reminds me of the spare (new) cam and end-plate I have for my Johnson RW pump. I should install those and see if it pumps more water, and stops the steam in exhaust I get at max revs. (40hp Lombardini)


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[deblen]

Originally Posted by daveNZ

Thanks Len, reminds me of the spare (new) cam and end-plate I have for my Johnson RW pump. I should install those and see if it pumps more water, and stops the steam in exhaust I get at max revs. (40hp Lombardini)


Sent from my iPad using Cruisers Sailing Forum

Some steam in exhaust is not necessarily abnormal. Depends a lot on your muffler design I think. If your muffler is low in hull & thru hull exhaust port is high,the water stays in muffler longer,waiting for enough exhaust pressure to build up & expel it.Make sense this water would get hotter. My VP 2003 exhausts in spurts because of this geometry.
The best indicator is your temp gauge-if it rises to boil point when under full power you may have a flow problem,among other possibilities.
First-check engine max RPM in Neutral-should meet specs. without overheating.
Then check RPM under full load @ full throttle. RPM should reach 90+ % of max in Neutral. If not,too much pitch,fouled prop/bottom,etc.
If the above seem normal,then look at complete RW system from inlet to exhaust for restriction.
If all OK,then remove fresh water t-stat & try again,etc.until you find culprit. Note: Replace t-stat for normal operation.
Proper coolant/antifreeze is important also.Never run pure water as coolant,except in emerg.Pure water doesn't carry heat away like proper coolant mix & boils at lower temp.

Cheers/Len

[mrm]

Originally Posted by deblen

[...]
Proper coolant/antifreeze is important also.Never run pure water as coolant,except in emerg.Pure water doesn't carry heat away like proper coolant mix[...]
Cheers/Len

I think this needs to be cleared up a bit. Specific heat of water is higher than s.h. of glycol, so water carries heat better than glycol for a given weight unit. However, the advice not to run pure water is correct because of antifreezing properties of such mixture as well as corrosion inhibiting properties (although, this may be more due to additional inhibitors found in commercial solutions). The rest of advice is spot on.

source: Ethylene Glycol Heat-Transfer Fluid

M.

[deblen]

Originally Posted by mrm

I think this needs to be cleared up a bit. Specific heat of water is higher than s.h. of glycol, so water carries heat better than glycol for a given weight unit. However, the advice not to run pure water is correct because of antifreezing properties of such mixture as well as corrosion inhibiting properties (although, this may be more due to additional inhibitors found in commercial solutions). The rest of advice is spot on.

source: Ethylene Glycol Heat-Transfer Fluid

M.

MRM- You just destroyed 40yrs of what I have been told & experienced.

So I read the link & what you say about the Specific Heat of water & that of e-glycol are correct!

But....perhaps the attached paragraph,copied from your link,is more in agreement with what I originally said. The mix of water & ethylene glycol "raises the boiling point" of coolant.



Cheers/ Len

[mrm]

Originally Posted by deblen

MRM- You just destroyed 40yrs of what I have been told & experienced.

Len, I am really sorry. Accept my apologies
I only mentioned it to keep this thread 'an excellent reference for the future'.
You are of course right, a higher boiling point is yet another good reason to use a glycol mixture as a coolant, rather than pure water.

Marius

[daveNZ]

Quick update. Nearly 3 years, (100 engine hours per year) and autohelm hydraulic pump motor that I repaired is still going strong. And I use it a lot!

[deblen]

Thanks for update! / Len

[daveNZ]

Now 2022, and the repaired autohelm pump still going strong! Interesting reading my own 7 year old posts. I recently saw that HyPro hydraulic pumps are available on NZ!

[deblen]

That's great!! / L

[mphillipsod]

Thanks for your help and info. Dismantled mine today. All hydraulic fluid drained out of pump after motor was detatched. Cleaned up motor that was full of black powder ( from brushes?) and reassembled. It runs in both directions but is pretty loud. Not a bearing whine, just noisy. Overhead lights didn't dim like before, so maybe drawing less current. Choice now is to refill with hydraulic fluid, or take the motor to a local shop for a once over. I'll sleep on it.