1988 4.3 omc water temperature

[lasko1]

My water temp gauge is runing about 180-190 on the muffs and in the lake ever since a buddy shut the water off to the muffs on me with the engine running for a couple more minutes.

I've replaced the impellar and housing kit. I've replaced the T-stat (160 deg) and the gauge still says 180-190. I pulled the hose off the T-stat housing and backflowed thru the power steering cooler with it's inlet hose off. I did get a couple pieces of impellar out of there. Hooked hoses back up (left the end going into T-stat housing off) and ran on the muffs again. I seem to be getting "good" water flow to T-stat housing with engine running for 10 seconds or so. Hooked everthing back up and still reading ~180 deg.

I've used an IR gun on the T-stat housing and on the manifold while engine is running and it says ~155- 160 deg. So, I'm thinkin its either the sending unit or the dash gauge that have drifted. Riser temps are both luke warm and am able to keep hand on them for long time. I did remove and clean off the sending unit too.

Has anyone else had the temp sending unit drift and read a "false" high? Or, have the temperature gauge in the dash read a "false" high?

Like I said, the gauge comes up slowly and then holds right at the 180 deg for as long as i run it.

Dave

 

[HT32BSX115]

Re: 1988 4.3 omc water temperature

My water temp gauge is runing about 180-190 on the muffs and in the lake............................................

Has anyone else had the temp sending unit drift and read a "false" high? Or, have the temperature gauge in the dash read a "false" high?

Like I said, the gauge comes up slowly and then holds right at the 180 deg for as long as i run it.

Dave

Howdy,


That's pretty common. Those gages are not all that accurate. They're just simple ammeters and the sender is just a simple temp-controlled variable resistor.......connected to ground..

You could get another gage and/or sender and see what it does but you may also have a poor connection from the sender to the gage.

As long as you have verified that you don't have a plugged t-stat housing, oil cooler/ps cooler (if installed) you're probably fine.

Sometimes those impeller fragments get stuck in the dam%#st places! They'll restrict or reduce cooling water flow....... reduced flow will cause over heats at high power settings.

Plugged (with rust) manifolds and risers will do the same thing........ because all the cooling water MUST exit the risers. If the risers or manifolds are plugged, the total water flow will be reduced but it might not be enough to make them run (really) hot although it usually does.

If it's a salt water engine and you haven't removed the risers and replaced the riser gaskets it a few years, now would be a good time to do it. When you get them apart, you can look inside and see if the water-jacket area has a LOT of rust clogging it..... If they're clogged, they need to be replaced. You cannot (or should not try to) "clean" them.


Regards,


Rick

 

[Lou C]

Re: 1988 4.3 omc water temperature

My old boat still has the OE gauges in it and they are pretty accurate from what I can see. I also have done some checking with an IR temp gun and what I have found is my temp gauge usually agrees with the reading I get from the intake manifold just under the thermostat housing. That will usually read 155-160 and the dash gauge will read 160-165. The manifolds (riser part of the one piece units) will usually be between 85-95* at idle on the water hose. The IR gun will read cooler on the rest of the thermostat housing, the only part I have found that consistently reads close to the dash gauge is the intake manifold right under the thermo housing. So go back and verify that. If you get close to the same reading then I'd start checking the temp sending unit.

The other test you can to is to put the boat in the water and disconnect the raw water intake hose at the thermo housing. Hold the hose up and have someone start the engine (briefly!) you should see a head of water at least 2" high come out of the hose. OMC says 2-4".

 

[lasko1]

Re: 1988 4.3 omc water temperature

This is a fresh water boat only.

Ok, I ran the boat til it came up to a "steady" temp on gauge (180-190) on muffs. I took lots of readings with the IR gun: 1st reading was on T-stat housing..160 2nd reading was right on manifold next to temperature sending unit.. 160 3rd reading was on front of engine where the big water hose goes into the front of the block at that pulley...160 deg.

So all my IR gun readings were 160 and the gauge still read 180-190. I have to believe I'm trully running at 160 but would like to see my gauge read that also for peace of mind.

I did remove the temp sending unit and cleaned all connections on it and also the cleaned the bottom of the temp sending unit. I think i'll just spend the $20 and see if the sending unit is slightly off. Other than that, if it still reads 180'ish, I may have to find another gauge.

 

[lasko1]

Re: 1988 4.3 omc water temperature

I installed a new temperature sending unit last night and the dash gauge read the same as the old one (180-190) once the engine came up to operating temp. I think I'll check the wiring on the back of the dash gauge. Also, I've read that if you ground out the wire on the sending unit end to the block, the dash gauge should peg out on the high side. That's exactly what happened when i tried that. Is it possible for the dash gauge to have oversprung and is just reading 20-30 deg high all the time now???

 

[Don S]

Re: 1988 4.3 omc water temperature

Replace the gauge, it's no longer accurate. It's not the first to do that.

 

[lasko1]

Re: 1988 4.3 omc water temperature

Anybody know where to get a matching gauge for my 1988 200 Horizon. I've found lots of temp. gauges, but I'd like to have something that matches the OEM gauges.

 

[Levinz11]

Re: 1988 4.3 omc water temperature

You might have to get a whole set of gauges if you want them all to match.

 

[Nivekt]

Re: 1988 4.3 omc water temperature

I see used gauges all the time on Ebay from older boats. Are you gauges made by Teleflex? Got any pictures?

 

[lasko1]

Re: 1988 4.3 omc water temperature

I'll check to see what type of gauge it is and see if i can upload a photo or two.....one of the front and one of the back.

 

[airdvr1227]

Re: 1988 4.3 omc water temperature

My water temp gauge is runing about 180-190 on the muffs and in the lake ever since a buddy shut the water off to the muffs on me with the engine running for a couple more minutes.

What condition was the impeller in when you replaced it? I'm thinking you've got bits and pieces of impeller clogging your cooling lines.

 

[lasko1]

Re: 1988 4.3 omc water temperature

Unfortunately, I don't remember what the old impellar looked like in regards to missing pieces. I have gotten 3 old impellar pieces out of my power steering cooler by removing the inlet water hose to the power steering cooler and blowing backwards from the raw water hose that connects to the T-stat housing. Are you thinking that some other pieces made it through the power steering cooler, through the Thermostat, and got into the engine and are partially clogging the water passages in the engine? I was wondering about that myself too.

I have pics of my gauge, it's a Medallion brand, but haven't figured out how to post them. I think I may have to set up a photobucket account.

I've found an OEM replacement gauge on ebay that I'm keeping my eye on. But before I make the purchase, I want to use a mechanical temperature gauge to verify what temp the water actually is. I should be able to remove the sending unit and just thread in the mechanical temp gauge and see what the comes up to. If it comes up to the 180'ish, then my gauge is still good and I've got a restriction. If the mechanical gauge reads 160 like the IR gun, then I know my dash gauge is bad.

You see, I took the temp of my pickup truck with the IR gun and it read ~20 deg lower than what the truck gauge read. So, I'm starting to think my boat gauge "may" be ok.

If debris made it into the engine water passages, what other indications (other than the higher gauge temp) would there be? Where else would I see elevated temps? And, what's the best way to get something out of those passages?