1995 130hp Johnson Overheating

I have a 95 130hp johnson. It overheats whenever ran at much more than half throttle. Tested it with heatgun, found out it always the starboard side getting hot. Both sides start out running close to the same temp (130 to 140deg) but after operating for a few minutes the starboard side starts to creep up then takes off to 170 deg plus. The alarm sounds and motor gos into slow mode. When I slow to a idle the temp slowly comes back down. I just bought this boat but the previous owner had overheating problems. He took it into a marine shop and they resurfaced the heads, put in two new waterpumps, and new thermostats. They thought they had the problem taken care of but I guess not. Since I've had it I put in another set of thermostats, then swapped new thermostats side to side still overheating on the same side. Took thermostats out and both sides ran the same temp. I've read about a pressure relief valve that can stick but don't know where to find it. Any help would be greatly appreciated. Thanks

Re: 1995 130hp Johnson Overheating

i would remove both tstats, and see if you get equal water out of them. might consider dropping lower unit, and back flushing system. also check compression.

Re: 1995 130hp Johnson Overheating

Removed thermostats and ran a little. Port side had three times as much water coming out of thermostat housing as the starboard side. Do you think something is plugged coming from the waterpump? I asume it should be closer to the same than that?

Re: 1995 130hp Johnson Overheating

Ok removed lower unit and backflushed. Did each side individualy (left one thermostat in at a time) then backflushed with both termostats out. Alot more water came out of the port side thermostat housing, is this because the housing on that side is lower than the starboard side? I took the head off the starboard side and couldn't see any thing that could be obstructing the flow there. Took a look at the water pump and it looks like brand new (it should because it only has about 5-10 hrs on it). Comp. tested all cyclinders and all of them were 120-125 psi. Took it out and the same thing happened starboard side heated up again. Getting very FRUSTRATED don't know what else to check. Any more help would be great. Thanks

Re: 1995 130hp Johnson Overheating

Take the vernatherms out and heat them in a pan of water; watch carefully to be certain that they both open at the same time. The pins can stick, so have them pushed in before you start to heat the water.

If the pins stick, you my want to replace the vernatherm.

The thermostat assembly may be damaged from earlier overheating or corrosion.

Re: 1995 130hp Johnson Overheating

Ok its been a while since I started this thread but still having the same problem. Got fed up with it last summer and just ran it without T-Stats. Then no problems, but I want to fix it right. Since my last post I've installed head temp gauges and a water pressure gauge. It has around 10-12 lbs pressure at idle and at about 3500 rpms it pegs out the gauge(30 lbs). Ran it on te lake this weekend still having the same problem. Everything is fine if you run it below 4000 rpms but if you are running above the starboard side starts creeping up till the alarm sounds. Port side gets up to temp. and just levels off. Anybody with any ideas I'de be very glad to hear them. Thanks

Re: 1995 130hp Johnson Overheating

The adapter housing water passage is blocked. The water comes from water tube to housing, then splits into two passages. The side with low water volume is blocked. You should be able to clear it by removing the head, and gearcase. Air pressure on engine side should blow out the trash. Trash could be in the housing or the block at the bottom.

Re: 1995 130hp Johnson Overheating

When you run without thermostats and it's ok
did you take it's temp? It should have been a lot
cooler. If so no restriction.
There should be a replacement spring that holds
in the diaphragm. It's a lighter spring.
The plan was to take care of the pain in the blank V4 overheat.
Shade tree repair, cut about 1 & 1/2 winds off the spring.

Re: 1995 130hp Johnson Overheating

What is the purpose of that lighter spring? Does it allow the diaphragm to open at higher rpms or does it just hold down the thermostat and diaphragm?

Re: 1995 130hp Johnson Overheating

The lighter spring does allow the diaphragm
to open easier allowing more water thru the
block at higher RPM'S

Re: 1995 130hp Johnson Overheating

Unfortunately, I don't have a solution, but rather a 1988 150hp Johnson with the same sypmtoms. Just replaced all thermo parts and starboard side is running hotter than port. I am getting a heat gun tomorrow so will know more specifics. Fellow before me took springs completely out of both thermos. There is a different head on starboard side that is higher compression than port (don't know why, before my time) so I'm wondering it thats part of whats going on. Anyway. I'll be watching thread for thoughts.....and contribute temps tomorrow evening.

Re: 1995 130hp Johnson Overheating

Thanks I'll give that a try and post how it turned out.

Re: 1995 130hp Johnson Overheating

First thing is to replace the impeller. number of hours is meaningless. If impeller has sat for years it will not work as well.
Has there ever been an impeller that broke into pieces, if so one or more may have made way in to the block and are blocking passages.

You should run with the t-stats in. Having them out will create hot spots in the engine.

Re: 1995 130hp Johnson Overheating

louluvscookies
I'm having the the same problem with my 1995 Johnson 130 have done everything you have done. I'm also getting alot of carbon build up on plugs. If you found something that works please post.