Overheating

[CaptWK]

I have 1993 OMC 454s in my Z33 and the starboard engine starts to overheat after running a while, 2800 to 3500 rpms. The temp gauge starts to climb up from around 145 to 175 then the shut down kicks in. If I stop before the cut out and pull back the throttle it heats up more. I throttle back up a couple of times and it cools right away and we start off cool again. I put a new impeller and thermostat in. Anybody been through this?

[MOP]

When was the last time the risers were checked, in salt 4 years is about the limit then chuck & replace. Sounds like the water is getting in but not out!

[KennyD]

What type of out drive do you have? If its an OMC then I have had this same problem, and it turned to be the housing in which the impeller sits. When I put in a new impeller I replaced that housing as well. It turned out that the new one I used was a bad part and allowed a small vaccum leak which caused my over heat. I re-installed the new impeller into the old housing and have had no problems since then. Check the impeller housing, or the O-ring seal, or the backing plate for a vaccum leak.

[CaptWK]

Yesterday I pulled the oil coolers and they were clean. The boat has 220 hours on the engines and drives and all but 20 are in fresh water. Next I took off the feed hose at the thermostat housing and ran the engine at idle and half throttle and was only getting a small stream of water either at idle or full throttle. I then put a clear tube on the power steering cooler outlet over to the thermostat inlet. Sure enough I was getting bubbles in the hose. Also I did the same check on the other motor and got a 6 to 8 inch stream of water that increased with rpms. So I pulled the impeller housing and noticed that half of the arms of the impeller are curved opposite of the rest. I had just put a new kit in a few weeks ago new plate cup and impeller. Maybe a bad set? Guess I'll replace the kit again. Anybody got an answer here for this...

[MOP]

Always notice the direction of the blades on any rubber impeller pump when pulling it apart, they must go back in the same direction if not they may not flip over to the correct direction. I have had engines diesel backwards not only did they suck in water but several have fliped a couple of blades loosing much of the pumps efficiancy. But it seems as if you may also have a vacuum leak as detected by the clear hose, look over housing carefully and do the correct sealing of the plate and housing, they can and will from side either side of the S/S plate. If you want to go overboard when its all together run a bead of silicone completely around the housing then if you did miss a spot it will cover your butt.

[RickR]

Do what MOP said but I use Permatex Hylomar instead of silicone.

I had problems with the copper pipe (between the upper and lower) sealing. Replaced the seals on top and bottom, cleaned the tube and used hylomar when installing.

[CaptWK]

Ok I checked all the hoses and put a new impeller kit in and I'm still not getting a good water flow to the engine. RICKR I guess I'll do what you did next. I watched the water comming in through the hose and it would start and stop pumping water. Is it possible that pump shaft could be slipping or leaking? frown

[RickR]

Captwk
While dissasembling, you can keep the roller bearings from falling out of the adapter housing by VERY LIGHTLY holding the impeller shaft (in the area where the impeller goes) with a DULL set of Vise Grips. DO NOT DAMAGE the shaft!

OMC says
OMC gasket sealer (for O-rings)
Adapter housing 9-11 ft lbs
Impeller housing 9-11 ft lbs

I would use Hylomar or High Tack (both Permatex products) and 9 ft lbs torque.

You can top off the late model King Cobra gear lube from the top, but you have to let the lube flow down before checking level.

BTW Inspect the gears and clean and relube the shift mechanism while you're there. :D

Poodle
Does the new housing pump more H2O? Looks like your 22 spent a lot time in the salt. Probably needs a new engine :rolleyes:

[CaptWK]

Ok guys here's what I found out today. I dropped the lower unit and found the seals for the pick up tube where loose fitting on the tube. Then I noticed a little corrosion around the pickup tube guide plate base and drive. So I removed it and found out that who ever built this drive never put an o-ring seal in the guide plate base. There was the grove but no seal. I'm guessing when it was new it sealed for a while but after time it started leaking. This explains the high speed overheating. Once I got up on plane it could suck air with the drive mostly out of the water. At low speeds the drive was sumerged and couldn't get the air. Thanks everyone for the help and suggestions. I will let you know how things go after reassembly. :)