www.iFourWinns.com

Thank you for your response,
so I'll check everything, I mentioned before, at this weekend.

I'll give an update on saturday.


Thanks a lot...

https://www.dropbox.com/s/ur4ny75jwrtd1 ... ousing.jpg

Here's what the inside of the thermo housing looks like from the factory shop manual....

_________________
88 Four Winns 200 Horizon
4.3 OMC Cobra-4bbl
2002 Walker Bay 10/2012 Suzuki 2.5
2008 Walker Bay 8

1998 Jeep Grand Cherokee 4.0/Selectrac
2007 Jeep Grand Cherokee 5.7 Hemi/Quadradrive II

Thank you very much for the illustratuion of the thermo housing.
Which tool ist the best one, to clean up the bypass. Is a solit wire or a screw driver enough?
Or is the rounding too tight for a solid tool?

A length of coat hanger wire will do.

_________________
88 Four Winns 200 Horizon
4.3 OMC Cobra-4bbl
2002 Walker Bay 10/2012 Suzuki 2.5
2008 Walker Bay 8

1998 Jeep Grand Cherokee 4.0/Selectrac
2007 Jeep Grand Cherokee 5.7 Hemi/Quadradrive II

Any chance that bypass can be cleaned by just pulling the hoses off or best just to pull off the housing altogether (trying to avoid replacing the .68c gasket)

Been watching this thread, mine running cool. Been doing too much landscaping around the house to play with the boat.

_________________
Jon Miller
1998 four Winns Horizon H200
Volvo Penta 4.3 GL
Newtown, CT

untitled-545 by millerjont, on Flickr

update:

today I tried to clean up the bypass of the thermo housing, but the bypass were really free.
After all I noticed, that the nut of the temp sensor cable were a little bit loose.
I tighten this nut and now the temp gauge starts before running the engine at the coldest temperature.
While running the engine you can see the, that the temperature will rise up to 120-125°F.

I think everything will work, but my temp sensor does not match to my instrument. I believe the resistance area of the temp sensor is wrong and I need a special sensor for my gauge.

After all the checking on this you might well be right. What I'd do is see if you can get specifications from the company that makes the gauges what the resistances should be. I still have the original Medallion gauges in mine and have not had to replace a sending unit either. All my cool running issues have always been sticky thermostats. But what you describe, for sure could be a mis match between the gauge and the sending unit.
In my OMC manual (1988 Factory Shop manual)
these are the specs for the temperature sending unit:
If the sending unit is suspended in water heated to the following temperatures, it should measure the corresponding ohms:
100*F=448 ohms +-10%
160*F=128 ohms +-7.5%
220*F=46.6 ohms +-5%

I don't know for sure, but does a 1995 boat have the gauge cluster that looks like an automotive instrument panel, with all the gauges in one panel (made by VDO) or the old style individual gauges? Because if its the VDO panel, these are known to be troublesome and cause issues with incorrect readings. Post a picture of what you have.....

PS, I looked in the 1995 FW catalog and the pictures that showed the instrument panel, all had that automotive style VDO panel. I bet that is your problem. Some people on here have replaced that with a custom made panel and individual gauges. Ultimately that's what I'd do.

_________________
88 Four Winns 200 Horizon
4.3 OMC Cobra-4bbl
2002 Walker Bay 10/2012 Suzuki 2.5
2008 Walker Bay 8

1998 Jeep Grand Cherokee 4.0/Selectrac
2007 Jeep Grand Cherokee 5.7 Hemi/Quadradrive II

Yes, you're right, it looks like an automotive instrument panel.

Do you know, where can I find a datasheet of my temp sensor.

The info would be in an OMC manual that covers boats that had that VDO panel...
I wonder if you temporily hooked up a standard gauge to your sending unit and a positive 12 v source and a ground would it read correctly... If the senders are made to the same spec I bet that would work. Your problem is most likely that VDO panel.

_________________
88 Four Winns 200 Horizon
4.3 OMC Cobra-4bbl
2002 Walker Bay 10/2012 Suzuki 2.5
2008 Walker Bay 8

1998 Jeep Grand Cherokee 4.0/Selectrac
2007 Jeep Grand Cherokee 5.7 Hemi/Quadradrive II

Yes, it could be.
But the gauge will work, when I'm shorting the wire and with the new temp sender. The mistake is, that the gauge will show the wrong temperature at all. I'm convinced, the temp sender is the wrong one and it should be replaced. I need a US standard and in germany you can only buy an european standard. Which sender can you buy in the US for the vdo panel in a FW Horizon 192 with an OMC 4.3GL?
I think the resistance range is wrong.

While that (wrong sending unit) is a possibility, those VDO panels were known to give bad readings. The only way to know for sure, is if someone on this forum has access to a manual that covers boats that used that instrument panel. Then you could look up the ohms specification at different temperatures. Keep in mind that this is not a Volvo or OMC engine per se. It is a standard, plain old Chevrolet 4.3 liter V-6 engine. As such, there is no European vs American sending units, the gauges can be different because they can be calibrated in metric units but the sending units I bet are the same. Its not even a metric thread in the intake manifold, I bet its an US spec SAE thread.

I would do the test I am suggesting with a normal gauge, see if it runs at the correct temp. Or even easier, get an infared temp measuring gun and measure the temperature on the intake manifold right under the themostat housing. If your engine is running at the right temp, with a 160* thermostat, you should see 150-155* F there. If so, then you can take out the sending unit and test it with an ohmmeter. As I listed the specs above. If that checks out and the engine temp is really correct as per the IR temp gun, it has to be the gauge, or wiring.....

look here at the resistance values for temperature gauges, you can see the ohms are the same for the corresponding C* and F* temperature ranges....


http://faria-instruments.com/site_manuals/IS0085E.pdf

_________________
88 Four Winns 200 Horizon
4.3 OMC Cobra-4bbl
2002 Walker Bay 10/2012 Suzuki 2.5
2008 Walker Bay 8

1998 Jeep Grand Cherokee 4.0/Selectrac
2007 Jeep Grand Cherokee 5.7 Hemi/Quadradrive II

Thanks a lot for your response.
Today I tested the old temp sender which was installed from the previous owner. I replaced it because of the issue. This sender has a resistance of nearly 200 ohms at 100°C/212°F. According to the specs of faria in your link, it cannot work with a "normal" instrument.

To test the instrument I'll install potentiometer with a defined resistance range at this weekend. Then I can see if it works at the right resistance. To find out the engine temperature I have to finde another solution, because I haven't an IR temp gun. I'll see and let you know.

Interesting that is another good way to test the gauge, dial up the specified resistance and see if the gauge matches it...

_________________
88 Four Winns 200 Horizon
4.3 OMC Cobra-4bbl
2002 Walker Bay 10/2012 Suzuki 2.5
2008 Walker Bay 8

1998 Jeep Grand Cherokee 4.0/Selectrac
2007 Jeep Grand Cherokee 5.7 Hemi/Quadradrive II

Is a workshop manual for my boat available?

Not sure but you can look for OMC manuals on ebay....
Keep in mind also the 94-98s were part of the joint venture years with Volvo so these models (Volvo Cobra SX and OMC Cobra) were identical in those years. Meaning that a Volvo service manual should work for yours. Keep in mine that sometimes even if the boat is a '95 the engine package could be a '94.
I've seen both Volvo manuals and OMC manuals and in my humble opinion the OMC ones are much better written and more clear.

_________________
88 Four Winns 200 Horizon
4.3 OMC Cobra-4bbl
2002 Walker Bay 10/2012 Suzuki 2.5
2008 Walker Bay 8

1998 Jeep Grand Cherokee 4.0/Selectrac
2007 Jeep Grand Cherokee 5.7 Hemi/Quadradrive II