HYDRECO Pump overhaul

[MikeP]

Pulled the Hydrecdo pump for the starboard tranny today. No real issue removing it though I had hoped I woudn't have to pull the intercooler. But I did - not for clearance but because I could not get a sufficiently long wrench on the large hose fitting to loosen it. If it hadn't been so tight, I could have pulled the pump without pulling the IC; there is sufficient clearance otherwise. I disassembled the pump. It needed new seals but outside of one rather odd item, everything looks fine. Here are some pics:

Think they used enough silicone? I HATE the way people apply this stuff!!!

The pump gears - just a car oil pump but a little bigger

Here's the odd thing. Note the slots for a key in the gear shaft and the drive unit? There was no key in the assembly and it is NOT a tapered fitting. Looking closely at the shaft and drive unit, it doesn't appear that there ever was a key installed - there is no wear or marks in either slot. Guess the factory forgot... As Forrest said, "You never know what you're gonna get." Once again, proof that if you didn't overhaul/repair an item yourself, you have NO idea what was really done, even by the factory. The parts diagram shows a key in there.

Here are all the pieces, some in plastic bags, and the rebuild kit which is just seals/orings, etc.

 

[chris piazza]

Mike was there a reason you rebuilt the pump? I can't imagine just regular maintainence. Low pressure? high pressure? My SB side is a little slow engaging is why I'm asking.

Chris
Superior Nights 53C

 

[rsmith]

I was always told they were throw aways. I've got the old cast iron ones that are supposed to be rebuildable but have never had to. I picked up a spare on ebay for $50 a couple years ago just in case. I heard the Hydreco's had a short lifespan like 500 hours but that was all hearsay from mechanics.

 

[rsmith]

Pulled the Hydrecdo pump for the starboard tranny today. No real issue removing it though I had hoped I woudn't have to pull the intercooler. But I did - not for clearance but because I could not get a sufficiently long wrench on the large hose fitting to loosen it. If it hadn't been so tight, I could have pulled the pump without pulling the IC; there is sufficient clearance otherwise. I disassembled the pump. It needed new seals but outside of one rather odd item, everything looks fine. Here are some pics:

Think they used enough silicone? I HATE the way people apply this stuff!!!

The pump gears - just a car oil pump but a little bigger

Here's the odd thing. Note the slots for a key in the gear shaft and the drive unit? There was no key in the assembly and it is NOT a tapered fitting. Looking closely at the shaft and drive unit, it doesn't appear that there ever was a key installed - there is no wear or marks in either slot. Guess the factory forgot... As Forrest said, "You never know what you're gonna get." Once again, proof that if you didn't overhaul/repair an item yourself, you have NO idea what was really done, even by the factory. The parts diagram shows a key in there.

Here are all the pieces, some in plastic bags, and the rebuild kit which is just seals/orings, etc.

Im supprised it didnt slip with only the nut and washer holding the shaft. I realy dont see why they would call it a throw away unless the pump housing wears out.

 

[MikeP]

The tranny was slow to engage on initial startup. Acadian suggested this is common with worn seals. The seals were all hard. That's why I am rebuilding it. I will rebuild the other as well- I can't stand non-symmetry!

As far as throw-away and 500 hours, that's silly. They appear to be original to the boat and there is no sign they were ever rebuilt. They show no particular wear and they are 30 years old. OTOH, since they are aluminum, if some serious grit got past the filters, the AL pump housing could be damaged beyond use. I don't know if the individual "hard" parts are available or not but if they are, the pump housing could be replaced by a new one.

 

[rsmith]

The tranny was slow to engage on initial startup. Acadian suggested this is common with worn seals. The seals were all hard. That's why I am rebuilding it. I will rebuild the other as well- I can't stand non-symmetry!

As far as throw-away and 500 hours, that's silly. They appear to be original to the boat and there is no sign they were ever rebuilt. They show no particular wear and they are 30 years old. OTOH, since they are aluminum, if some serious grit got past the filters, the AL pump housing could be damaged beyond use. I don't know if the individual "hard" parts are available or not but if they are, the pump housing could be replaced by a new one.

Looking at the silicone job I would say someone has been there before. Can't see the factory leaving the keyout of the keyway.

 

[MikeP]

The silicone was from when the engine was worked on by the previous owner and the pump had been removed/reinstalled. But the pump shows no sign of ever being opened up. THe white paint on the pump was quite uniformly yellowed where the rest of the engine is much "whiter," the engines having been rebuilt when the PO owned it (and by someone who was intensely fond of silicone ). As I noted, the slots in the drive and the shaft have no "impression" that would be there if the key had ever been in place.

I may be wrong but I really don't believe there was ever a key in the slot.

 

[GJH]

Yeah, i did this last year. Maybe your picture is not complete or there is more stuff in that envelope, but there were a kajillion little seals and o-rings and such. I let an experience mechanic do it, but watched most of the project. I lack the requisite fine motor skills, and am a little dyslexic, not a good project for me. Mine was leaking oil so we just did the whole thing "while we are in there". The other side had been done when the PO had that engine rebuilt a few year before. I agree, if it hasn't been done go ahead and do it, because stuff breaks in pairs on all these boat things.

 

[MikeP]

Maybe your pump was a different brand/model that used more parts - I don't know anything about whether this was the only pump used on these engines.

There are around 15 seals/orings/gaskets (I didn't count them) in the kit and there are no additional seals/gaskets/rings in the pump that aren't replaced by what's in the kit.

 

[MikeP]

Reinstalled the pump and checked operation. One issue fixed, the other unaffected.

The internal leakage in the pump whereby the pressure would go up as I turned the screw but then abruptly drop at around 120 as I continued to turn the pressure screw no longer occurs. The pressure will continue to rise as long as I keep turning, as it should.

However, the sluggish engagement of the transmission after the engine is first started is still there; the pump overhaul had no effect on that. So the diagnosis from Acadian that the seal kit would correct the problem was sadly incorrect...

Oh well - it has no affect on actual operation, just on the first engagement after engine startup. I can't figure out what actually happens differently after the engine has been shut down for a while and restarted as opposed to operating and going in/out of gear. There is no delay at all if in gear, then in neutral, then back in gear (forward/reverse).

THe lag after startup does not change regardless of how long the engine has been idling before engaging "forwared" and pump pressure is correct.

 

[rsmith]

How long is the delay? If I run the boat every day I have no delay at all but if it sits for more than a week I get about a 3 sec delay before it engages.
I always bump it in and out of gear before I take the lines off. Something in the trans must bleed down while its sitting.

 

[MikeP]

My starboard tranny has about 5-6 second delay on first startup after an overnight shutdown. I agree it seems like something is bleeding down BUT since the pump is running as soon as the engine spins and the tranny pressure is at 120-125 at idle, any bleed down should be immediately pumped back up. It doesn't matter how long the engine sits at idle, after the first start up, it will delay going into gear. This initial startup shift delay has been increasing over the past couple of seasons.

 

[rsmith]

Mike what did you ever decide was the issue?

 

[MikeP]

I had another conversation with the folks at Arcadian. Brian suggested to just ignore it and that the initial delay after first startup is quite common with some transmissions. He said that some internal leakage is causing it but there is no reason at all to open up a transmission since it causes no problem in actual operation subsequent to the first shift into forward of the day.

So I'm leaving it at that though I will rebuild the other tranny pump anyway.

HOWEVER, I must admit that if a Mopar 727 tranny was doing the same thing in one of my various street or strip Mopars back in the day, I would have jerked the tranny and rebuilt it immediately! And to be perfectly honest, the only thing stopping me from doing it with the M20 is the fact that it weighs 350 lbs!

 

[krush]

How much was the rebuild kit?

The slow initial engagement probably occurs because in all the arteries of the tranny, the oil leaks out of the engagement circuit due to old age. Having the biggest pump in the world won't affect this much because there is no flow through the circuit when in neutral.

 

[MikeP]

"Having the biggest pump in the world won't affect this much because there is no flow through the circuit when in neutral."

Yep, absolutely right!

The kit is about 75 bucks.

 

[randy]

Does the kit come with instructions and drawings or parts only?

 

[MikeP]

Mine came as parts only. There are exploded views of the pump available on line. I downloaded one while on the boat. Unfortunately, I am back in Mexico now and I don't have the site info or download on this computer. Wasn't too hard to find. It's pretty straightforward and the absence of instructions is not really a hinderance. The diagram IS useful because it shows you what is supposed to be in the pump which may NOT be what's actually in there!

 

[GJH]

I am pretty sure I downloaded this from Acadian's site.