470 overheating, is this normal flow through the heat exchanger?

[blkzoe]

Re: 470 overheating, is this normal flow through the heat exchanger?

Just a note on "healthy" 470 coolant temps. My 170hp's (twins); at a constant 4000 rpm run at about 170 degrees. They mirror eachother. As soon as I come down off plane they rapidly cool down to 140 or less. Thermostats are 160 degrees; heat exchanger is 4" variety. No oil cooler. Vessel is an '86 255 Amberjack; i.e., 5500 lbs. with a real deep "V".

NOTE: flush the heat exchangers on a regular basis; both raw water and fresh water. Good flow here makes for a healthy 470 and a happy owner.

 

[dccordell]

Re: 470 overheating, is this normal flow through the heat exchanger?

Good advice blkzoe, thanks! I cleaned out the heat exchanger back when I began work on this boat/motor. I took the entire exchanger off the motor, checked every tube, and I soaked the inside of the tubes and the closed coolant side with something I can't remember (maybe muriatic acid?), so it was very clean. I think I will pop it back open this evening just to double check everything inside.

I got the water pump service kit (impeller, upper housing, all gaskets, slinger, etc) at the local shop today. A little pricier but I do have it today, so that's worth something. It will be going on tonight...

Quick question: what is the purpose of the water slinger on top of the upper pump housing? I noticed my old housing didn't have this slinger at all.

 

[Volphin]

Re: 470 overheating, is this normal flow through the heat exchanger?

You don't have any kinked or collapsed hoses do you?

 

[blkzoe]

Re: 470 overheating, is this normal flow through the heat exchanger?

Quick question: what is the purpose of the water slinger on top of the upper pump housing? I noticed my old housing didn't have this slinger at all.

Uh, sling water?

 

[dccordell]

Re: 470 overheating, is this normal flow through the heat exchanger?

You don't have any kinked or collapsed hoses do you?

None as far as I can tell. I do notice that the closed cooling hoses from the intake to the camshaft pump, and from the exhaust manifold to the heat exchanger are hard, almost like there is a spring or some other sort of "anti-collapse" material inside them. Is this normal? Are these hoses "anti-collapse" and hard intentionally? I was going to order these hoses new, but sheesh, they are so expensive from factory, and mine don't leak, soooo....

Uh, sling water?

Haha, I can't argue with that! More specifically, what is the reason to sling water in that area? Is it to help cool the internal area there from the exhaust gases? Just curious on this one...

One other question: In Chris's alpha water pump service video, he says to not put the o-ring back on the top of the drive shaft in the groove when reinstalling the lower to the upper. Is this the case on the MC-1 drives, too? No o-ring in the groove?

 

[dccordell]

Re: 470 overheating, is this normal flow through the heat exchanger?

Well, good and bad news...

After replacing the water pump housing and impeller, I just could NOT get the lower unit back on the upper, even though everything was lined up as far as I could tell. It would get about 1/2 - 3/4 inches there, then stop. Still not 100% sure why it wouldn't go, but I thought it was because of the shift shaft. It was hanging down, and wouldn't stay in place in the upper unit, and would jam when the lower unit tried to push it up as I lifted up on the lower unit.

So I pulled the upper unit off and... LOTS of drive oil came rushing out of the u-joint bellows. So now everything is just laying on the ground out there.. ugh!

Could this be the oil seal on the drive shaft? I'm doing some searching on here, and in the manual, but is this a tough item to replace? It looks like I'll need that big wrench...

And the good news: I can look down in the upper unit water passage, just above the water pump tube, and I can see a few pieces of old impeller in there. I don't know how I missed them last time, but there they are, so hopefully that is causing my overheat issues.

One problem leads to another!! Any advice on the oil leak?

Edit: I'm going to start another thread for the oil leak since it seems to be a totally different issue. Hopefully the water passage blockage is the cause of my overheating issues, but that seems to be moved to the back burner for the time being.

 

[Bt Doctur]

Re: 470 overheating, is this normal flow through the heat exchanger?

The upper shoe rests on the lower , dosent stay up in the upper one.
lubricate the impeller with soapy wayer, liquid soap,etc.
lower unit in fwd(spline turned fully clockwise.)
raise unit untill you can get the front nut started by a thread or two
now set the shoe onto the spline making sure it points in a straight line and the prop is still locked CCW.(fwd)
raise unit a bit to engage the splines by turning the prop CCw about an inch or so.you`ll feel it drop in place
start the side nuts first making sure the shoe does not jam itself in the upper part and that there is a bit of play.
tighten side nuts, then remaining nuts.

 

[dccordell]

Re: 470 overheating, is this normal flow through the heat exchanger?

Bt, that's basically how I went about trying to reinstall the lower, but the part of setting the shoe onto the spline kept messing things up. The shoe (assuming that is the part in the upper) kept getting crooked and binding things, so I finally gave up and figured I would put it together with the upper off of the boat, leading to my new set of problems.

Hopefully it will be easier to put back together off of the boat.

 

[stonyloam]

Re: 470 overheating, is this normal flow through the heat exchanger?

Hopefully it will be easier to put back together off of the boat.

It will be:joyous: Just make sure it stays in forward (lower ss all the way CW, hold CCW pressure on prop shaft).

 

[Volphin]

Re: 470 overheating, is this normal flow through the heat exchanger?

Great find on the pieces of impeller! Don't get frustrated with her... take your time and do it right. That oil is nasty stuff. Sometimes you just have to take a break and walk away for a bit.

 

[dccordell]

Re: 470 overheating, is this normal flow through the heat exchanger?

Sometimes you just have to take a break and walk away for a bit.

That's exactly what I did yesterday evening, especially as it was getting dark and the mosquitoes were coming out to get me, not to mention the ants that had been crawling up my shorts all afternoon!

 

[Volphin]

Re: 470 overheating, is this normal flow through the heat exchanger?

And those little mosquitos down there are nothing to sneeze at! They'll drain a man in 30 min.

 

[dccordell]

Re: 470 overheating, is this normal flow through the heat exchanger?

Well, hopefully this is the main cause of the overheating issue. These pieces were jammed up in the water pocket in the upper unit. I was able to fish two of the pieces out through the horizontal water channel that leads into the gimbal housing, but that last piece was stubborn and ending up falling back into the water pocket.

I had to pull the water pocket cover off to get it out. Hopefully it's all cool water temps from here on out! :happy:

The pieces were hiding here and here:



And here's the culprits here:

 

[ktbarrentine]

Re: 470 overheating, is this normal flow through the heat exchanger?

First...you were extremely lucky to be able to get the water pocket cover off without breaking bolts! Excellent job! And good to get the old pieces out.
Next... Now you need to address your yoke seal issue. Probably a good idea to do a pressure test to confirm, but sounds like the symptom really stands out. Your either into a new yoke shaft, of a speedy sleeve, or you can seat your new seal about 40 thou deeper to get a new bite on the existing yoke if it is in fair shape. There are some very recent threads on this repair (as well as info in the stickys, old threads, and in your service manual). If you need guidance through that seal repair...the forum is here. (rolling torque vs pinion nut torque...your probably an old enough drive to have the nut torqued vice having to do rolling torque). (Note...if you plug the oil passage port, you can pressure test your upper independent of the lower.... I often do both independently before I reassemble, then do a total pressure test to finish it off before oil fill).
Next.... Sage advice is to leave the O-ring off the vertical shaft as achris advises....as this Oring is notorious for interfering with the lower of the two seals in the upper drive, which then leads to water in the splines, and more problems down the road. The lower seal (actually a grease seal to keep grease in the splines and water out of that area) does the job of the O-ring.
Lastly...You will be very pleased when reassembling your upper to your lower off the boat....much easier to be able to see whats going where when looking into the exhaust passage (guiding water tube into place, vertical shaft into place, etc. Just remember to keep the shift shaft fully clockwise and the prop locked CCW as earlier advised while you reassemble.
Best of luck!

(edit...just re-read where you started a new thread on the oil leak (and I've posted in it already!!! Pay attention KTB!)...so you've got the gouge you need in that thread..... You already way past what I posted here.....)

 

[dccordell]

Re: 470 overheating, is this normal flow through the heat exchanger?

Thanks kt, I had read of the difficult nature of those water pocket bolts, so I was extremely careful removing them... a little reluctant even. Three of the bolts came out easy, the fourth was tight, but I was real easy with it and went slow... it came right on out.

All parts and tools are on the way to repair the upper seal, hopefully back together by this weekend! I have another thread going in that job...