mercruiser 5.0 mpi overheats at idle

[achris]

Re: mercruiser 5.0 mpi overheats at idle

Hhmm hum ---- anybody ---- water pocket cover, in the bottom of the top box..(it's an Alpha one, NOT a gen II). Needs a clear plastic hose in the first water hose to check for bubbles... I could be (and often am) wrong...Let's just check it anyway.

Chris
(feel free to say "Oh, shut up Chris....". Everybody else does)

 

[JustJason]

Re: mercruiser 5.0 mpi overheats at idle

SHUT UP CHRIS

Just kidding ya.

Wether your right or wrong.... you are ultimately correct because part of diagnostics is figuring out what the problem is but also spending time ruling out what the problem isn't.

 

[achris]

Re: mercruiser 5.0 mpi overheats at idle

SHUT UP CHRIS

Just kidding ya.

Whether your right or wrong.... you are ultimately correct because part of diagnostics is figuring out what the problem is but also spending time ruling out what the problem isn't.

And that's an easy one to test... shouldn't take too long...

 

[nauticool]

Re: mercruiser 5.0 mpi overheats at idle

Update. Bell housing is back on with new bellows and water hose. Waiting for pump base to arrive so I can put a complete new pump in and refit lower unit.
The base looked melted in parts. If you look at the pics I put on you tube you will see the lower unit before I removed the pump. Just above the pump on the shaft is a rubber washer/o-ring that looks as if it had popped out of the top of the pump, could this have been my problem I'm wondering. Also there is a small spring type o-ring, not sure where this is from?

The boat did work all summer but like I said I don't do a lot at idle and it takes maybe 5-10 mins to overheat from cold.

It was an invoice not estimate and boat went in with a stalling issue when put into gear. This was rectified by changing the shift cable and re routing it. They also changed bellows water pipe and pump at the same time.

So the pump base comes Wednesday so should be able to test by the end of the week.

 

[achris]

Re: mercruiser 5.0 mpi overheats at idle

....The base looked melted in parts.

Sure sign of running without water... The pump base (plastic) got hot enough to melt... The water pocket cover (also plastic) is a lot closer to the exhaust.

If you look at the pics I put on you tube you will see the lower unit before I removed the pump. Just above the pump on the shaft is a rubber washer/o-ring that looks as if it had popped out of the top of the pump, could this have been my problem I'm wondering. Also there is a small spring type o-ring, not sure where this is from?

Part of the lower seal from the top box? If things got hot enough to melt a rubber seal, imagine what would have happened to a plastic water pocket cover.

The boat did work all summer but like I said I don't do a lot at idle and it takes maybe 5-10 mins to overheat from cold.

It was an invoice not estimate and boat went in with a stalling issue when put into gear.

This can be caused by the shift shaft seal being burnt by hot exhaust gas. Water then seeps into the bushing and makes the shifting mech tight... causing a stall when shifting into gear. Hot exhaust gas can also deform a water pocket cover.

This was rectified by changing the shift cable and re routing it. They also changed bellows water pipe and pump at the same time.

So the pump base comes Wednesday so should be able to test by the end of the week.

......

 

[nauticool]

Re: mercruiser 5.0 mpi overheats at idle

What is the water pocket cover? Is it, what I am reffering to as, the base of the pump?

 

[achris]

Re: mercruiser 5.0 mpi overheats at idle

No, the base of the pump it effectively the top of the lower gear housing. The water pocket cover is up inside the bottom of the top housing. Most people miss it completely.... When an engine runs without water the exhaust enters the exhaust system without being cooled. That will affect anything plastic in the exhaust system, and the cover is plastic. They get hot and distort, allowing exhaust gas into the cooling system and causing 'overheating'. They can be (and usually are) an absolute b1tch to replace. Access is difficult and the s/s screws lock up in the housing, then shear off and have to be drilled out and the hole re-threaded.... not nice... I've seen grown men cry over these thing... It's item #3 in this picture....

 

[nauticool]

Re: mercruiser 5.0 mpi overheats at idle

Thanks for that. Will check it tonight and, if I'm feeling daring, unscrew it and have a closer look. Still concerned about this spring. Could it be from the Oil seals, item #26 on your diagram? Are they hard to change?

 

[nauticool]

Re: mercruiser 5.0 mpi overheats at idle

Thanks for that. Will check it tonight and, if I'm feeling daring, unscrew it and have a closer look. Still concerned about this spring. Could it be from the Oil seals, item #26 on your diagram? Are they hard to change?

 

[achris]

Re: mercruiser 5.0 mpi overheats at idle

Thanks for that. Will check it tonight and, if I'm feeling daring, unscrew it and have a closer look. Still concerned about this spring. Could it be from the Oil seals, item #26 on your diagram? Are they hard to change?

I suspect it's from the lower of the 2 seals (item#21). Rather than trying to remove the water pocket cover, just do a visual and if it looks ok (no signs of melting) then re-assemble and check the water flow (inside the boat) with a piece of clear plastic hose.

 

[achris]

Re: mercruiser 5.0 mpi overheats at idle

Oops, double post.... Sorry.

 

[nauticool]

Re: mercruiser 5.0 mpi overheats at idle

My mistake, I meant #21. The rubber seal looks ok but not sure about this spring. Will put it back together without it then

 

[achris]

Re: mercruiser 5.0 mpi overheats at idle

You'll need to replace that seal. It's really easy. Part # for the seal is 26-96503. Just flick the old one out with a screwdriver and put the new one in, with the lip facing out/down.

Chris.......

 

[nauticool]

Re: mercruiser 5.0 mpi overheats at idle

Would you guys be kind enough to tell me if this is where the round spring came out of

http://www.youtube.com/watch?v=Zh6ebBYLxkg

Dealer says the gears need to come out but i think he must be talking about the upper oil seal, is the lower one to stop water going up and the upper to stop the oil coming out/down.... makes sense to me anyways.
The seal in the picture is very hard. Can i just put a cut down one side to peel it out?

Water pocket cover looks ok

Thanks

 

[achris]

Re: mercruiser 5.0 mpi overheats at idle

 

[Fishermark]

Re: mercruiser 5.0 mpi overheats at idle

You can usually just pry it off. Here's one I did recently. It was so bad you couldn't even tell a seal had been there:

Here's the old one (or what's left of it) and the new seal side by side:

 

[nauticool]

Re: mercruiser 5.0 mpi overheats at idle

thanks fishermark. looks like this one gets missed quite a lot. new seal comes tomorrow so hopefully can put all the outdrive back on and test for overheat

 

[nauticool]

Re: mercruiser 5.0 mpi overheats at idle

in the upper pump rebuild kit there is a black rubber washer/o-ring about 1/4" wide and it looks as if it will fit in the void inside the top of the pump but all the diagrams i have show it outside of the pump on the shaft? plus on my original pics before i removed the pump it was on the outside. i thought it had been forced out. Nearly there, testing tomorrow

 

[achris]

Re: mercruiser 5.0 mpi overheats at idle

Are you referring to #41? If so, it goes on the outside of the top of the water pump housing....

 

[nauticool]

Re: mercruiser 5.0 mpi overheats at idle

The very same. And #17 presumably at the top of the shaft? Sorry for being picky but want this to be perfect. Clymer manual is not that clear and this is the first time i've worked on Mercruiser. Will take half, or even quarter ( yeah right), the time next time..... I hope