AQ125A overheating, but only above 2500rpm

[Mullin]

I just got back from a weekend on the colorado river. Had a good time and all but my boat was overheating anytime I got the rpms over 2500. Once over 2500 the temps would just climb and climb, no difference if I was at 3000 or redlined at 5000 rpm. Then I'd back it off to 2000 and it would cool back off pretty quick to its normal temp of 180.

First thought was an airleak in the leg. But I just replaced the water connection and hose on the intermediate while I replaced the bellows. I noticed that it would overheat both on plane and at 2800 rpm not on plane. I'm not sure of the water level on the drive at that lower speed though. When I changed the water connection, I noticed the tube's plastic bushing below was breaking apart, I'm wondering if this could be a source of an airleak.

Then I decided to pull the impeller (didn't change it this year). It looked pretty darn good with just a little wear on the fins but nice and flexible.

I talked to a local boat service shop owner while out there and he said something I didn't think of and was wondering if this is in fact a 'known' symptom. Anyway, he said he's seen it several times before, the high rpm's get the raw water pump shaft deflecting and causes an air leak on the shaft seal right on the back of the water pump. He suggested a pump repair kit with a new shaft, seal, and bushing. He knew he didn't even have one on hand so it's not like he was just trying to sell me parts or something.

I took the pump apart and inspected the shaft and seal. The shaft has a little bit of a ridge cut into it from the seal and the seal had a little wear aside from looking pretty darn good. I did notice that I could deflect the shaft a little by hand, not enough to make a gap between the seal, but it moved a tad. I ended up using a little fine grit steel wool and smoothed out the shaft a little. It actually seemed to inprove by about 400 rpm until it started overheating. (first day I had to back off all the way down to 2000-2100 rpm, day two I could do 24-2500rpm)

So to sum this thing up, I probably need to do both repairs. The water pump is easy but costs $100 for parts, and it sucks to spend a hundred if you don't have too. The bushing in the leg is $10, but is going to be a real PITA to do. I just had the upper apart and don't want to press out the tube for a questionable fix.

Thanks for reading my wall of text, if you have any insight on this problem or tips for either repair option I'd love to hear it.

 

[captmello]

Re: AQ125A overheating, but only above 2500rpm

I think you are on the right track. I replaced the upper bushing you mentioned a few years back. If it's bad it certainly could cause some movement at that point and effect the seal of the specialized gasket beneath the intake elbow. Its not an easy, quick fix, since you need to pull the entire outdrive, but I didn't find it difficult at all. If you boat in salt water that may make it a bit harder if its corroded in.

I cant speak about the water pump issue...

Good luck!

 

[Mullin]

Re: AQ125A overheating, but only above 2500rpm

Its not an easy, quick fix, since you need to pull the entire outdrive, but I didn't find it difficult at all.
Good luck!

Thanks. Yeah it just looks heavy and difficult, but at least the parts are cheap. So, I was going to see if I pull the upper and then drop the lower, could I then tap out that tube enough to slide in a new bushing and then tap the tube back up? I do boat in salt water and removing the whole drive seems a bit daunting to me.

 

[captmello]

Re: AQ125A overheating, but only above 2500rpm

It's another one of those labor intensive, just to swap out a few seals, type job. I doubt you will be able to just slide it in because the Suspension fork, where the seal sits, needs to clear the intermediate before the bushing can be replaced.
When I did mine, I built a rolling stand to support the outdrive so I could just roll it right up to the rear of the boat for easy assembly. Use the tongue jack to height adjustment.

Maybe rebuilding your water pump is easier, but if you can see that broken bushing, I think you know what needs to be done. Now or later... Boating season is only so long.:grumpy:

 

[Mullin]

Re: AQ125A overheating, but only above 2500rpm

Yeah I know you're right. Funny, I was actually just reading your treads from back in '08 and '09 when you had the same type of problem.

So did you ever even rebuild the raw pump or just sealed up the leg, or both?

 

[captmello]

Re: AQ125A overheating, but only above 2500rpm

Yeah I know you're right. Funny, I was actually just reading your treads from back in '08 and '09 when you had the same type of problem.

So did you ever even rebuild the raw pump or just sealed up the leg, or both?

I went back and read those to. boy was I a newbee. Thanks to Don S for being so patient with me, I might still be struggling with it today.

So, looking back, I think initially it was the hose connection/elbow and or gasket causing the higher RPM overheating. But even after that it still overheated. Somewhere along the line, researching, reading, I found I had some play in the pivot tube upper bushing. If I were to lift up on the outdrive, you could see some play in that area. Knowing the that gasket in there needs to seal the gap between the tube and the suspention fork, I figured movement couldn't help any. So that winter I pulled the whole drive and brought it inside to pull the pivot tube and resealed the needle bearings and replaced all the bushings while I had it apart. I didn't post about that project for some reason, but I did take pics.

The one thing that has always bugged me a bit, is that when I replaced the intake elbow and gasket the previous summer, I had found the gasket to fit a bit snug and wanted to pop out of the groove around the top of the pivot tube. Well, I got it on as best I could. fast forward to when I had the outdrive in the garage, having reassembled it with the new bushings, etc. I went to install the intake elbow/gasket. Again the gasket didn't want to sit in the groove, but I got it on the best I could, trying to hold it in place, etc. Once I got it installed, I reached my finger into the mouth of the intake elbow and I could feel all around the edge of the matting surface where the fitting holds the beaded gasket in place. Sure enough, I could feel where the gasket was not seated properly and beaded part wasn't in the groove. It was going to leak air for sure. I was able to loosen the intake fitting just enough to push the portion of gasket that was not fitting properly right into place. For all I know that may have been the problem from the time I replaced the fitting and gasket originally. But I'll never know...

I have not tried to feel inside the intake fitting with the outdrive installed so I can't say if it can be done. but if i were to replace one, I would be trying to get a finger in there to feel from the inside. Perhaps that is your next move. Pull the hose and try to feel in there.

And, no, I never did any more work on my water pump. Once I got it to stop wobbling, It has been fine ever since. Sadly this boat and motor have been used only once or twice a year since buying the pontoon. I miss the speed and sound of the V8, but the Admiral calls the shots...I keep thinking I should get rid of it but I just can't. Sorry to ramble.

 

[Mullin]

Re: AQ125A overheating, but only above 2500rpm

Awesome stuff mello, thanks for elaborating!

I already have a new bushing and plan on replacing it for certain sometime soon. But then I added up all the extra seals and o-rings and the needle bearing and specialty tools for removing/installing it all and was up to about $170. So I' going to take it apart first and see what I really need and don't need. And i'll definitely take a good look at that gasket/seal the way you described.

I think I can rule out the pump with a little test. I just need to put her in the water this weekend and run it at high rpm but not in gear. I know that while the boat is sitting still the leg and all the air problems are underwater, so if the temp rises then I'll do the pump rebuild too. If it stays cool, I'll put that $100 towards something else on the boat, there is always something else!

Funny, since I got the bayliner I hardly ever go out on the pontoon anymore! And my poor little Valco (Lucky Charm) has only gone out maybe twice. I proposed on the Lucky Charm and my wife won't let me sell it!

 

[captmello]

Re: AQ125A overheating, but only above 2500rpm

I didn't use any special tools and I was able to reuse the needle bearing cage. From what I can remember, I just did the two needle bearing seals, upper pivot tube bushing, two pivot pin bushings. I think that's it beside's the orings, etc for the reassembly.

I'm not sure about your test. Without load you may not be able to work the motor to an overheat and we all know you shouldn't race the engine without load anyway. I can see where your going with it though. Imo, If your getting good flow to the strainer at high rpm, which you could test by running up the rpm's briefly, It should be cooling. As you know, water should be spraying out of the strainer assembly with the cap removed. Wet and messy, but could tell you if your loosing flow at higher rpm. Just thinking out loud...

You said you were in salt water, what's the condition of the exhaust manifold?

 

[jerryjerry05]

Re: AQ125A overheating, but only above 2500rpm

Profile? Location? Salt or fresh water?
If the pickup parts(in the drive) are good then.
Cooling at slow speed:getting hot above a certain RPM???
1st look at the manifold.The 125a 1981-84 if it's original it could be corroded.
Loosen and check the end for corrosion.Then check for flow.
It should flow out as much you put in.
It's almost 30 and probably WAY past needing a new one.
Second: the heat exchanger also going on 30.Probably full of sand and sediment?
You might get lucky and backflush or even take to a radiator shop for a acid soak?
Usually once they are clogged they need replacement.
The water pump. The wearplate? Any grooves?The rear wear surface?
Any deep grooves anywhere?
The cam in the pump,it will wear down after time.It's an easy replacement(maybe) just 1 screw.

 

[Mullin]

Re: AQ125A overheating, but only above 2500rpm

I didn't use any special tools and I was able to reuse the needle bearing cage. From what I can remember, I just did the two needle bearing seals, upper pivot tube bushing, two pivot pin bushings. I think that's it beside's the orings, etc for the reassembly.

I'm not sure about your test. Without load you may not be able to work the motor to an overheat and we all know you shouldn't race the engine without load anyway. I can see where your going with it though. Imo, If your getting good flow to the strainer at high rpm, which you could test by running up the rpm's briefly, It should be cooling. As you know, water should be spraying out of the strainer assembly with the cap removed. Wet and messy, but could tell you if your loosing flow at higher rpm. Just thinking out loud...

You said you were in salt water, what's the condition of the exhaust manifold?

Good news about the tools. I was thinking of just picking up the drift for setting the seals and bearing, and it's pretty cheap.
Yeah the test isn't flawless by a long shot. Yeah I took off that strainer cap once, that was fun.

Manifold looks good. I replaced the boot on the end of it last year and it looked good, from what I could see anyway.

Profile? ?Location? Salt or fresh water? both
If the pickup parts(in the drive) are good then.not many parts, but no, some bushing is shot
Cooling at slow speed:getting hot above a certain RPM???yup, see first post
1st look at the manifold.The 125a 1981-84 if it's original it could be corroded.
Loosen and check the end for corrosion.Then check for flow.
It should flow out as much you put in.
It's almost 30 and probably WAY past needing a new one.looks good to me
Second: the heat exchanger also going on 30.Probably full of sand and sediment?
You might get lucky and backflush or even take to a radiator shop for a acid soak?
Usually once they are clogged they need replacement.looks great inside. Had it off when I changedd the coolant circulation pump, nice and shiny inside
The water pump. The wearplate?? Any grooves?The rear wear surface?
Any deep grooves anywhere?no the raw water pump looks pretty solid aside from a really tiny groove on the shaft from seal wear, not leaking water out but maybe air in?
The cam in the pump,it will wear down after time.It's an easy replacement(maybe) just 1 screw.I was just noticing how only the volvo rebuild kit comes with that cam. I couldn't imagine it wearing down but I guess after 30 years...maybe.

Thanks for the fresh ideas!

I'm going to try and re-set the hose connection on the leg. Then get it wet saturday and see if I can't rule out or include the pump. Then I'll pull it apart next week and hopefully have it ready for the next weekend. I'll let you know how it goes.

 

[Aq130c-Mike]

Re: AQ125A overheating, but only above 2500rpm

I would check the thermostat. Maybe it is not opening fully or it is stuck in a partially open position. Maybe it is enough water to cool the low rpm but the high rpm is too much heat for the little bit of water that is getting through. I am new here, but it didn't seem like anyone mentioned it in any of the threads. Might be worth a shot. Good luck.

 

[Mullin]

Re: AQ125A overheating, but only above 2500rpm

I'm going to try and re-set the hose connection on the leg. Then get it wet saturday and see if I can't rule out or include the pump. Then I'll pull it apart next week and hopefully have it ready for the next weekend. I'll let you know how it goes.

I was able to pull the hose off of the water connection and tried to get my finger in there to feel around for the gasket...mello must have some E.T. fingers! j\k man, but I couldn't get my fingers in there far enough to feel the gasket. So ended up pulling off the hose connection instead. The gasket had been cut by the tube. I think because my bushing is gone now, the tube has slop and moved around and cut the gasket.

I put it back together for now and when I lowered the drive I saw water leaking our from where that bushing is supposed to be. It was there before the river trip, but not anymore. I guess it finally broke into small enough pieces that there is nothing left.

Weather has been crappy here this week so I'll hopefully get to it this weekend when it warms back up a little.

 

[Mullin]

Re: AQ125A overheating, but only above 2500rpm

I couldn't wait 'til the weekend and started taking it apart this evening.

I pulled the lower unit and all three seals look like crap. Trying to find them is proving difficult. There is a seal on the water connection, one on the oil screen, and one big o-ring around the drive shaft. The drive shaft o-ring I think I found, 925256 #44 Lower Gear Unit: 832701 : 832701 - 7742840 - Volvo Penta

Any leads on the others?



in this last image, the three rings are from bottom to top; the large o-ring, the strainer and seal, water pickup tube seal broken into two.
Then off to the left next to the strainer is a metal ring. It came off from the water pickup area but not sure exactly what it is or where it goes. Maybe part of the busted up seal?

 

[captmello]

Re: AQ125A overheating, but only above 2500rpm

#24, #34 in this link

Intermediate Housing: Drive 270 - 7742840 - Volvo Penta

To bad you couldn't get your fingers in the intake fitting, You will be able to with the outdrive off however. I've got double jointed fing...no, not really. But it looks like you found your air leak.

 

[Mullin]

Re: AQ125A overheating, but only above 2500rpm

Cool thanks. I didn't think #34 was right, but looks like it's just the same part number anyway.

I ran out of light last night and stopped with just getting the lower pulled. Took some pics and wrapped everything up and went in for the night. It snowed last night! Only a light layer, man I thought it was getting cold out there last night :snowman:

 

[Mullin]

Re: AQ125A overheating, but only above 2500rpm

I pulled the upper last night and have just the intermediate housing left still attached to the boat.

I was hoping to knock out the tube (book calls it the steering knuckle) in place. Well I gave it a few good wacks and it's not budging. So, looks like I need to go ahead and remove the inter-housing and use a press like the book says. I couldn't get the out the lock screws that retain the pivot pins, this is why I wanted to do it in place. I'll hit them with the impact screwdriver tomorrow.

 

[Nickypoo]

Re: AQ125A overheating, but only above 2500rpm

The tube is difficult for sure but you should be able to do it with the right size punch and a 3lb hammer. A regular nailing hammer wouldn't budge it for me but the 3lb did.

Of course if you have access to a press that would be the way to do it.

But you won't be able to do the job with the drive in place either way. You need to reinstall the tube to the correct depth and I don't see how that's possible with the drive still connected to the boat.

 

[Mullin]

Re: AQ125A overheating, but only above 2500rpm

I was swinging with a 2.5 pounder but couldn't really get good strikes with it mounted. Then I figured I'd never get it back together this way so it's gotta come off. I'll see tomorrow!

 

[Nickypoo]

Re: AQ125A overheating, but only above 2500rpm

Good luck. I think you'll find it much easier with it off the boat.

 

[captmello]

Re: AQ125A overheating, but only above 2500rpm

Now I see why I didn't post pics of the work I did on the pivot tube. They are almost too backyard to post on this forum, but I'm going to risk the backlash and show you one or two pics as you go. In fact I'll most likely remove the pics after you've seen them so people don't think you're the one using this method...

In this pic you can see I used a spark plug socket to "press" out the tube, just happened to fit nicely. Remember, my boat has never seen salt. I can't remember how hard I hit it, but it came out fine. This is risky because you don't want to mushroom the end of the tube.

Pics Deleted for obvious reasons...