Hot 150 - Possible fix?

[garyj]

I bought a 1987 150 XR2 last October. Have ran it on several occasions. From the time I bought it, it always ran great. Trouble is, if I keep it at or below 4000 rpm's everything is fine. Over 4000 rpm's and the HOT alarm will sound. I had installed a new water pump after the very first time the alarm went off. The water pump housing looked great. I installed a temp gauge last weekend and the temp reading is around 215 at 4000. Anything above will peg the gauge and the alarm will sound. To start with the trouble shooting, I checked the poppet. Seems to be working okay. Next I ran a compression check. The top and second cylinder on the starboard side reads 112 and all the other cylinders read 115. Think the top end is okay. I then dropped the lower unit, and this is where I have a question concerning the plastic connector that connects the waterpump to the pickup tube. The plastic connector sits down in the waterpump housing fine, but where the plastic connector fits over the pickup tube, its loose as a goose, sloppy, floppy!! Should there be a grommet or seal that would seal the plastic connector to the pickup tube? I can't imagine how the pump could pressurize the motor with this kind of fit.<br />Any help would be appreciated.<br /><br />Thanks...Southern Catfisher

 

[tmcalavy]

Re: Hot 150 - Possible fix?

Try a short cut-to-length sleeve of the right size rubber hose to seal their connection. Nothing to lose, cept the buzzer/alarm.

 

[KCLOST]

Re: Hot 150 - Possible fix?

Yes, <br /><br />Look at part#'s 28 & 37<br /><br /> Water Pump XR2

 

[garyj]

Re: Hot 150 - Possible fix?

Thanks,<br /> After looking at the parts diagram, I now realize that the plastic sleeve is there only to line up the pickup tube to the water pump when the lower unit is replaced. The pickup tube actually slides completely through the sleeve and then into the rubber seal in the water pump housing. <br />Well, back to the hunt. The water pump housing looks to be in great condition. I guess the next step would be to back flush the system. Any ideas on the best way to back flush??<br /><br />Southern Catfisher.

 

[achris]

Re: Hot 150 - Possible fix?

I have just spent about 3 days trying to fix this problem on a friends engine. He finally gave me the clue I needed when I took the poppet out and he said that the spring looked a lot heavier than the one he remembered. Turns out that the cracking pressure was a tad on the high side. I cut one coil off the poppet spring and all is sweet! <br /><br />Chris............

 

[KCLOST]

Re: Hot 150 - Possible fix?

You do have that Part #27, which is the rubber seal, don't you, in addition to the guide sleeve?

 

[garyj]

Re: Hot 150 - Possible fix?

KCLOST, <br /> I do have the number 27 seal. Didn't realize it at first as it is down in the water pump outlet. Also have the sleeve. Thanks for the diagram.<br /><br />acris60,<br /> I took your advice and clipped the spring a tad.<br />Maybe get to try it this weekend if the weather permits.<br /><br />Also read some post concerning back flushing. I removed the lower unit. and thermostat housings and backwashed from the top down into a clean bucket. No trash or debris. Inserted the hose over the pickup tube and got a huge amount of water out the stat outlets. Don't seem to have any restrictions.<br /><br />Got one question though (full of questions), I tried to use the water hose at the poppet port, and cannot get any water to spill out the rectangle exhaust ports. (Putting water in the outside cavity of the poppet contraption, not in the block cavity if that makes sense)Should I be able to see water at the rectangle ports??<br /><br />Southern Catfisher

 

[KCLOST]

Re: Hot 150 - Possible fix?

Not when the engine is not running...<br /> <br />And don't try that when the engine is running....<br /><br />You only want water entering the engine through the pump intakes to ensure proper cooling and water passage...<br /><br />Back pressure and exhaust is what causes the water to exit the upper exhaust ports when running at higher rpms...

 

[garyj]

Re: Hot 150 - Possible fix?

Thanks KCLOST,<br /> I kinda figured that, but it great to hear it from someone with experience.<br /><br />Since I am new to this, could someone please explain where the excess water is channeled when the poppet opens. Is it going straight into the exhaust and dumped, or maybe routed around the exhaust or other parts to aid in cooling before being dumped? Still trying to make sense out of this poppet thing of how water can be dumped and still cool the engine??????<br /><br />Also, I am getting ready to re-install the lower unit. I have read about a "water dam" between the water pump and the exhaust housing. If what am looking at is correct, I have a gasket along that divider. Should I also use a sealant on this gasket?<br /><br />Thanks<br />Southern Catfisher<br /><br />(By the way, a pic of my old Boat.)

 

[CU2NITE]

Re: Hot 150 - Possible fix?

You could have an obstruction in the water jacket cover(the cover thats on the front of both heads) Also a bad head gasket will cause over heating. Look at the plugs if one is washed out I would suspect a head gasket. Just my two cents. Good luck and let us know.<br />CU<br /><br />-------------------<br />RUNNING THE MOTOR WHILE LISTENING TO THE HORN WILL MAKE YOU MORN!!

 

[achris]

Re: Hot 150 - Possible fix?

Mr Catfisher (may I call you Southern?),<br /><br />I've scanned the water flow diagram in for you, but the picure site I use must be down so I'll try again later.<br /><br />Chris............

 

[garyj]

Re: Hot 150 - Possible fix?

CU2Nite,<br /> If when I try it this weekend, I still have the overheating problem, the heads removal are next. I have compared all spark plugs and I don't see any difference that would indicate water in a cylinder. They all look pretty much the same. Will let you know.<br /><br />achris60,<br /> Sure, you may call me Southern, although I am not as far "South" as you. You are way down under!! Thanks for the effort for a water flow diagram. I would really like to see and understand the actual flow.<br /><br />Thanks..<br />Southern Catfisher

 

[achris]

Re: Hot 150 - Possible fix?

OK, here's the diagram.<br /> <br /><br />

<br /><br /><br />Good luck.....

 

[garyj]

Re: Hot 150 - Possible fix?

Thanks achris60,<br /> From what I am seeing (I'm kinda hard of seeing), the poppet valve is dumping HOT water from the bottom of the heads, only when enough pressure is achieved to open the poppet. If this is true, then it would make sense at higher rpm's and WOT the valve should be open to relieve pressure and would also be dumping lotsa HOT water. Also makes sense, if the spring is too strong, and doesn't allow the valve to completely open, hot water could not be dumped quick enough to keep the engine cool. Am I seeing wrong???? Could the differences in the spring tension of poppet valves be related to some of these engines running hotter than others??<br />Just thinking here...<br /><br />Southern Catfisher

 

[achris]

Re: Hot 150 - Possible fix?

Mr Southern,<br /><br />Absolutely correct. The difference in the engines is not so much the spring pressure of the poppet, but the output pressure of the water pump. You can also see from this the importance of having the thermostats in place.<br /><br />Give me your e-mail address and I'll send you a better, full size, copy.<br /><br />Chris...............<br />(mahi01@iinet.net.au)

 

[garyj]

Re: Hot 150 - Possible fix?

Hey, Thanks achris60,<br /><br />E-mail - garyj@frontiernet.net<br /><br />Gary (alias - Southern Catfisher)

 

[Outrage 19]

Re: Hot 150 - Possible fix?

Hi achris60 cound you send me a copy of that too? Thanks namaddage@aaahawk.com

 

[garyj]

Re: Hot 150 - Possible fix?

Well, just an update. Took the boat out for a try this morning. I still have an overheating problem. These are the things I have done.<br /><br /> Removed lower unit and inspected water pump <br /> (pump is only 3 months old)and housing. It all <br /> looks new. Used sealant for water dam between <br /> water pump and exhaust housing.<br /><br /> Back flushed engine. Doesn't seem to have <br /> obstructions.<br /><br /> Checked thermostats Checked good.<br /><br /> Checked poppet. Clipped a couple of rounds off <br /> the spring.<br /><br />Checked compression - 112-115 on all cylinders.<br /><br />Water pressure looks good at the tell-tale at low and high rpms and also good water discharge at the upper exhaust ports at medium to high rpms (even though it is running hot)<br /><br />Have ordered a water pressure gauge and will install to be sure pressure is sufficient.<br /><br />If the water pressure is good, I'm thinking head gaskets or obstructions in the water jackets. Have checked for differences in appearance of spark plugs, but all look the same, no indication of water in a cylinder.<br /><br />What gaskets do I need to replace? Just head and head cover gaskets, or other gaskets?? Anything else I should be looking for?<br /><br />Any help would be most appreciated....<br /><br />Southern Catfisher

 

[CU2NITE]

Re: Hot 150 - Possible fix?

If you replace the head gaskets, there is one for each side, same with the water jacket cover. Cost about 50 bones for the head gaskets and about 10 for the water jackets. Make sure you have a manual so you know what you should torque the bolts back to. It's a fairly easy process. When you take the heads off, clean all the old gasket off and lay the head face down on a flat surface to make sure they aren't warped. Good luck and let us know.<br />CU<br /><br />-----------------<br />RUNNING THE MOTOR WHILE LISTENING TO THE HORN WILL MAKE YOU MORN!!

 

[CU2NITE]

Re: Hot 150 - Possible fix?

Replace head gaskets (2) and replace water jacket gaskets (2). Make sure you have a manual so you know what to torque the bolts back to. Very easy procedure. When you have the heads off put them on a VERY straight surface to make sure they aren't warped. Good luck and let us know. Also I have had a situation much like yours, thought that pump looked good but when I finally changed it all was better. Just my two cents. Good luck and let us know.<br />CU<br /><br />----------------------<br />RUNNING THE MOTOR WHILE LISTENING TO THE HORN WILL MAKE YOU MORN!!