1990 ProV 150 Overheating

[99yam40]

best to start a new thread with all of your info including your motor ID info

[Joe06351]

I am dredging this up from the past because I am having the same problem. I suspect the previous owner or before didn't replace those two parts. I wonder if anyone can tell me the part numbers that I need to do the job right? Also what is a good pump repair kit? Thanks, Joe.

[Keithbaja]

A complete w/p kit does NOT come with the black rubberish gromlet (outlet). Dont know why. Kinda goofee IMO
its almost a complete kit !!

[panasonic]

Sometimes parts diagrams are not correct and/or clear. And no matter how many people complain about it they may never get fixed....Glad it worked out for you.

[dust1300]

I found this post after trouble shooting an overheat issue for several weeks after an impeller change on a new to me Yamaha 1991 Pro V. I took the impeller apart several times to check my work. I checked the thermostats and poppet valve. All was good and working. The boat has only been in fresh water. I knew it had to be something with the water pickup tube but I couldn't figure it out. I noticed the two holes in the top of my old and new housings for something to snap in but nothing came with the new housing (impeller kit) and nothing was inside the old housing. I checked two schematics I found online and neither showed those two components. I saw this post and then went to a Yamaha dealer because they at least had the rubber sleeve that goes down inside the housing. They couldn't find the white plastic fitting that snaps into the top of the housing in their inventory so they grabbed a housing they had scrapped and salvaged the two pieces (rubber seal, white plastic spacer) and gave them to me for free. An hour later my boat was running fine. I'm not sure why those pieces wouldn't come with an impeller kit. Those are more important than new bolts. Those two pieces are maybe $9 worth of parts. But without them is catastrophic. Glad I found this post!

[MNY4m4h4]

A photo of the plastic cover that clips onto the top of the housing. When I bought the water pump kit this was not supplied. There was also a rubber seal not supplied.

Well the exact same thing that was your issue was mine. I looked at my old housing and sure enough that plastic cover and the rubber seal were in the old housing from 2 years ago when I first replaced the water pump.

I swapped those pieces into the lower unit and tested her at the launch. Ran smooth as butter for 15 minutes and no alarm!

Words can't describe how good it feels. Its like I just got a brand new boat!

Many blessing to you and yours and may fortune find you early and often!

Thank you to all who took time out of their days to read this thread and help out.

[midgiegualla]

A photo of the plastic cover that clips onto the top of the housing. When I bought the water pump kit this was not supplied. There was also a rubber seal not supplied.

[midgiegualla]

It was a long time ago but I think there were two parts. One rubber seal that went into the top of the housing and then a plastic sort of a bush that pushed onto the top of the housing. It' easy to miss when your not looking for it. But if your old housing hasn't got one then it could be the problem ???

[MNY4m4h4]

Just a thought. I have a 1990 115 V4 . About 10 years ago I changed my water pump. I bought a kit and fitted it. All went well (at least I thought) When I started the motor I had a weak stream from tell tail. I knew I had done something wrong ??? I pulled it apart again but all looked good. After scratching my head for a while I realised that the new water pump housing didn't come with the plastic insert/seal on top. I went to the bin and got the old seal off the top of the old housing I had thrown away and fitted it to the new one. Fitted it and all was good !!! So I'm thinking that maybe this seal (from housing to water tube) has been lost at some stage and you don't realise it is missing ???

This is a good possibility.

I did save my old housing so I will look for it, but previous owner could have tossed the seal when they initially put in a new impeller.
I will look for this seal.

What does it look like, is it rubber?

[midgiegualla]

Just a thought. I have a 1990 115 V4 . About 10 years ago I changed my water pump. I bought a kit and fitted it. All went well (at least I thought) When I started the motor I had a weak stream from tell tail. I knew I had done something wrong ??? I pulled it apart again but all looked good. After scratching my head for a while I realised that the new water pump housing didn't come with the plastic insert/seal on top. I went to the bin and got the old seal off the top of the old housing I had thrown away and fitted it to the new one. Fitted it and all was good !!! So I'm thinking that maybe this seal (from housing to water tube) has been lost at some stage and you don't realise it is missing ???

[MNY4m4h4]

If the popit valve is somehow stuck open would I read zero pressure at idle or is this most likely the water pump?

Obviously the hose had enough pressure on it to put out a lazer beam stream from the tell tell, but I wonder if it was so much pressure from the hose that it was masking the issue at low RPM, as like you stated without the lower unit attached there is no water flow function being performed by the power head.

I have always had good cooling at speed in the water, which would naturally increase the pressure on its own.

What kind of pressure will a properly working water pump put out at idle?

In theory I could hook the hose back up and back off the spigot on the hose to a water pressure that would simulate a working water pump at idle and see if it goes into alarm

I'd like to narrow this down and see if I should be buying a new pop it spring (I just replaced the grommet) or if I should just buy a whole new water pump assembly and try that one more time.

So far you guys have been a great help…..I felt great to see that good stream last night.

Thanks in advance.

[99yam40]

Using wrong parts are the only thing I can think of at this point

I dropped the lower unit and hooked up the hose to the water tube and before I even started the motor it was pissing way more than it was at the launch.

With water pump( lower unit) removed starting the motor will not increase water flow

[MNY4m4h4]

Update:

I dropped the lower unit and hooked up the hose to the water tube and before I even started the motor it was pissing way more than it was at the launch.

I started it up and let it run for 10-15 minutes and got no alarm. The water pressure gauge does work and was reading 18-20 PSI.

I did make a video but I don't know how to upload it. I can pull the heads and extract 8 snapped off bolts in the block (not head bolts) but I can't post a video...lol

So it's probably the water pump....what could I have done wrong when I replaced it?

[MNY4m4h4]

Prima faces sounds like water pump - they are fickle
You said burning on previous pump housing; this raises the possibility that a previous impeller may have also broke leaving a small piece stuck in a passage somewhere. I hope not because if the case you may again have to pull it apart.

Thought the same initially as it made sense, which is why I pulled it all apart specifically looking for a chunk of an old impeller lodged someplace in the system but found nothing. All I found was clean water jackets, not that that is a bad thing but was hoping to find an obvious blockage.

[zenoahphobic]

Reverse flushing into thermostats housing with thermostats removed. But don't spray water everywhere.