www.iFourWinns.com

The temp gauge on my VDO display does not have numbers on it so I am not sure what temp the marks mean. I have a 1998 h200 with the VP 5.0GI engine which I believe has a 160 degree thermostat. It used to idle with the gauge showing just above the first mark. Now it seems to hover around the Middle mark when idling. It does not overheat but I am thinking the impeller might be getting weak. Could anyone tell me at what mark their boats run when at idle? Or what the temp marks mean in degrees? Thanks.

When was the last time you replaced your impeller?

This is the first summer with the boat. The previous owner said he had just replaced the impeller and gave us the old one which was a jacobson(not VP). It looked well used but OK. He gave us the old fuel pumps which he replaced in last couple years. He said he also just changed the engine oil and outdrive oil. Both checked out ok but I dont know what kind of oil or brand of impeller. We had no reason not to believe him. The boat runs perfectly. It has just under 400 hours. I am of course watching everything carefully and have always been concerned about impellers. I have a VP brand in my hand should I believe it needs replacing. In any case it will be changed next Spring along with proper VP oils.

My son bought a 2006 h200 several years ago with 40 hours on it and the previous owner who he knew had taken it to the dealer every year for whatever needed to be done. Upon purchase we changed out the impeller. Very easy job on his boat. It looked old (maybe original), was missing one blade, and was a "Johnson" brand. You never know what you get when buying used. We always follow strict PM using VP products only. We just changed out his impeller again this year. The VP brand looked new after over 100 hours.

FWIW,
Almost all VP branded products are NOT made by VP. Just has their name on it.
For instance, they do not make, props, fuel pumps, impellers, seals, gaskets,oil,grease, to name a few.

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One of 4 Previous (Sold) Boats:
2000 Four Winns 268 Vista

Current Boat: 2004 Chaparral 235 ssi cuddy

My VDO gage reads just below half (about 40% of scale) once the engine warms up. Stays the same at idle or cruise. I also have 1 160deg thermostat.

One of the first and easiest diagnostics of your impeller is to check the temperature of the top of you exhaust riser elbows. You should be able to keep your hand on this location during idle or cruise. "almost too hot" to keep your hand on them during cruise is still acceptable. Better still is to use an infrared thermometer to get a real temperature reading there and other locations. A measurement of the intake manifold right next to the thermostat housing should read about the same as the temperature gage at the dash.

If your engine is running hot, but your manifold risers are normal, then you should suspect a bad thermostat. Secondary, a bad temperature sensor or gage.
(all raw water pumped in goes out the manifolds, even if the thermostat is not opening).

If your manifold risers are very hot, then you are not getting enough water pumped by the raw water pump. This can be (in order):
1. Bad impeller
2. Clogged (rusty) manifolds/risers
3. Clogged intake screens or passageways at the lower unit

If it is Clogged manifolds/risers (#2 above), then your large water hose will feel quite firm with the engine running.

If your engine runs hotter at idle than it does at higher rpms, then you probably have a bad impeller and/or worn waterpump housing.

Ray

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"Knot Easy" 2000 Horizon 240 Volvo 5.7GS /SX
tow: 2017 Honda PILOT EXL-AWD
prev. boats:
'87 Chaparral 198CXL 4.3 OMC Cobra
'69 Jetstar 16ft Ski Boat, 115hp Yamaha
'68 Aluminum Jon Boat, 3hp Sears
'64 Water Wings

Anytime you have temp questions, it is a good idea to get an IR temp gun, I have one on the boat that I use to keep tabs on the cooling system. I have found that the area right under the thermostat housing most closely reflects the temp you will see on the gauge, but about 10-15* lower than the gauge. My engine idles at 160 and the most it will get to is about 175 which is right after coming off plane. The risers are usually 95-105 at idle, and the hottest I have seen them get to is 135-140 right after coming off plane but they cool off to about 115 pretty fast.

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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

I will do more testing as Ray suggested. It seems that near middle of the gauge might be OK. Lou suggested an IR temp gun. I will get one of those. Any recommended Brand or type? Thanks for the replies.

There are quite a few but I have 2 from Radio Shack. They work fine and are a great diagnostic tool for boaters, because boat cooling systems tend to be more troublesome than vehicle cooling systems because of raw water cooling. Even closed systems, which depend on raw water to cool the antifreeze can be more troublesome than cooling systems on vehicles. You can tell if your engines running at the right temp and you can tell if your exhaust system is getting enough cooling water to keep the temps in a safe zone. If the exhaust system overheats it can be a hazard because it can allow water in the boat due to burning up rubber exhaust hoses that connect the exhaust risers to the exhaust Y pipe.

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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

I don't think there's a lot of difference between them until you get into the Fluke line, which is $$$ and totally unnecessary for automotive/boating use. I have three Raytek MT6 units (shop, truck, and tool bag) that have been bulletproof for 12+ years now.

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Mike
2005 Four Winns 230/240
VP 5.7GXi/DP
1998 F-150 XLT
Boat Pic

I have a Harbor Freight IR temp gun and it seems to work well also. ($30)
http://www.harborfreight.com/non-contact-infrared-thermometer-with-laser-targeting-69465.html

_________________

"Knot Easy" 2000 Horizon 240 Volvo 5.7GS /SX
tow: 2017 Honda PILOT EXL-AWD
prev. boats:
'87 Chaparral 198CXL 4.3 OMC Cobra
'69 Jetstar 16ft Ski Boat, 115hp Yamaha
'68 Aluminum Jon Boat, 3hp Sears
'64 Water Wings

I added a cheap set of gauges in the engine compartment to help verify some things when I was troubleshooting my VDO cluster. The temp sensor is particularly easy to install as there is most likely a spare port for the sensor on the engine (at least in my 4.3 there was)

Good Luck.

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

untitled-545 by millerjont, on Flickr

I'd say if you already have a new impeller in hand, go for it. It can only help and prevent and then you'll know. You can also test for premature excessive wear if in fact the current one is new. If you have that, you'll narrow your next solutions. An impeller swap is a somehat easy task. If you have similar concerns post swap, move to the next diagnostic situation.

Good luck!