www.iFourWinns.com

So I started my winterizing process today. Part of the plan this year was to replace the thermostat (160F) since at the end of the season the temp always seemed to run on the cooler side (better than too hot I guess). Thought maybe something was stuck in their keeping it open. After removing that cast iron piece and all the hoses I discover that my thermostat is missing parts!

So where does everyone think it was likely to end up? Do I have to go and find it? Thanks.

Was the whole thing missing, or just the spring? If the whole thing was missing someone might have removed it in the past to solve an overheating problem. If just the spring was missing, then someone might have substituted an automotive stat and it could have rusted off. Since the coolant flows from the t-stat housing through the big hose to the front circulating pump take that hose off look inside it and in the inlet of the water pump. Also look in the intake manifold right under the stat housing.

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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

It is atleast missing the spring if not more..


It doesn't look much like the new one I purchased (from Sierra). I removed the water pump (to service it) and didn't find anything in there. I couldn't see very far into the intake manifold under the stat housing but that is where my feeling is of where it would have fallen (due to gravity).

Wow never saw that in all the years I've boated in salt water...You can jack the front bow down, or have someone do it while you look in the manifold to see if you can grab the spring.

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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

you could also get a flexible pick up with a magnet on the end and see if you can find it that way

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1989 245 vista
5.7 cobra

I would say that is an auto thermostat just from the looks of it. The flexible magnet is a good idea.

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2008 Four Winns h180 Bowrider
3.0 Volvo Penta

2013 Dodge Durango HEMI

So i fished and I fished and I never found a single component of the old thermostat. So I called it and put everything back together with a new thermostat and O-ring.

Started the boat up for the very first time this year (kicked right over!!!) and everything seems to be OK at first. Then I noticed the engine temps starting to rise above normal (190ish then even higher). I had good water flow and it was pouring out the exhaust bellows as normal when I run on the hose. I don't think the hot water from the engine is getting to either of the exhaust manifolds since they were very cool to the touch.

Suggestions? I am not sure what else to do besides try a new thermostat but this one "tested" fine on the bench.

Also could someone tell me the ID of the hose that goes from the front mounted raw water pump to the thermo housing? I need to get a clear, reinforced length to trouble shoot this issue but now I can't get to the boat.

Thanks

Seems like that hose is 1.25", but not sure.

I think the new thermostat is faulty, or at least take it apart again to see if the crap from the old one came around and clogged or jammed it. Not much else it could be, except maybe the temp sensor (not likely). If your manifold temps are cool, then your getting plenty of raw water flow.

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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

One way to tell what's going on, without taking everything apart:
Get an IR temp gun ($40 or so at Radio Shack).
Warm the engine up on the water hose. Start taking readings:
Cold engine, the raw water intake hose and the manifold feed hoses will be about the same temp (65-75* or so). As the engine warms up, check the temp of the intake manifold right under the thermo housing. I find that this spot follows the temp gauge on the dash but is about 10* lower, consistently. The max this should read at idle is about 155*. At that point the stat is starting to open. You should see 160* on the gauge. The way to tell is to also check these hoses:
Big hose from the thermo housing to the circ pump: with the engine cold it will be about 100-120, but when the stat opens it should go up to 140 or so. Also another sign of the stat opening is that the manifold feed hoses will get hotter, like going from 75* to 95*. This is because when the stat is closed, hot water does not flow out of the engine,the cold water coming in just goes out the exhaust. The water flows into the stat housing and then goes thru that by pass in the housing to the manifold feed hoses.
When the stat opens, it allows warm water to flow out of the block and to the manifold feed hoses. The cold water coming in from the raw water intake hose gets sucked into the neck of the stat housing and flows thru the block and heads. Then exits on top from the stat housing out to the manifolds. So do some checks you may have a defective stat or maybe it's not opening till 180-190*.

Manifolds cool but engine hot as Ray said points to a stat not opening. I've always used OE stats and never had not opening issues, only not closing issues because of rust, sand etc keeping it from closing.

In my OMC manual it says run the engine till the temp exceeds 160, if the manifold feed hose is cold the stat is stuck closed, if the hose is warm the stat is open.

_________________
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 guys. This is just the info I need. My Seloc manual doesn't do a great job here and only gives two seperate tests...and not what the temps should look like. I should just pickup a new thermostat just to be safe for the next time I get to the boat. Where do you get OEM thermostats? Most listing on ebay say "OMC/Volvo" and list the correct part numbers but I guess you are never sure what you are getting.

I am also going to pickup some 1" clear tubing so I can check for air bubbles as part of this troubleshooint.

Forget the internet for a bit. Go and find and patronize, either a Volvo Penta dealer or Evinrude dealer that can order OMC parts. You have a joint venture model so the OMC/Volvo parts are identical. The only way to be sure you are getting the right stuff, is to go to a dealer that looks it up in a parts book. Some of the online retailers I have used that are good are
http://www.crowleymarine.com (look in OMC parts)
http://www.dougrussell.com (same) but really I think do it yourselfers do better with a real store, where the guy behind the counter actually knows something. The guys who sell me my parts are professional mechanics.

If you want to do the air in the cooling hose diagnosis, google
"Volvo Penta Overheat Diagnosis". This is a PDF file that tells you exactly how to do this. I actually did all the tests in it (except on my Cobra the hookups are a bit different because the impeller is not engine mounted). What I found was that it was not air in the cooling water, but reduced flow due to marine growth build up (moored in salt water boat) in the lower unit water intakes. So every 3 seasons or so I split the lower and upper drive housings and I clean out that area and paint it with Trilux-33 anti fouling for aluminum.
If you really want to shop the 'net, you can look on the volvopentastore.com site, make sure to have your model # though. Volvo's model numbering system is confusing to say the least.

PS what engine do you have? The V-6/V-8 stats are the same, housing is the same. Same as the OMC design for the same year.

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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 have the Ford V8, 302.

Model # 502ACPMDA

http://www.crowleymarine.com/johnson-ev ... /42171.cfm

you need parts 3, 4 and 5.
Note that your number is actually an OMC model # not Volvo. But it does not matter.
But if there is not a close Volvo Penta dealer and there is an Evinrude engine dealer they can order OMC parts from BRP...

On yours the design is a bit different than the Chevrolet engines, with an elbow adaptor that thats attached to the intake manifold and the standard OMC V6/V8 thermostat housing sits on top of that.

_________________
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

Reporting back.

So had some success today on the water. Had clear hoses installed from the water pump to the thermo housing and one from the thermo housing to one of the exhaust manifolds (to check for bubbles). Had an IR gun at the ready to take the measures as the boat was running about 900-1200 RPM.

Temps at startup (Left manifold / Thermo Housing / Right Manifold)
72 / 74 / 73

Temp on dash gage reading 150F
78 / 124 / 78

Temp on dash gage reading 160 (stat should be open)
82 / 152 / 82

After that the gage on the dash continued to go all the way up to 240 but the engine temps didn't get hotter. They stayed in this range:
92 / 162 / 90

After running for a while at the dock like that we took it out (under load) at slow speed continuing to check the temps and they all stayed here. We check temps at the sensor, thermo and the elbow. You could alway touch all of those parts which agreed with the IR readings in the 160-165 range. Took it up onto plane and ran some more and the temps dropped slightly (even more water flow) and when we came back down to an idle engine stayed with readings as above. This makes me think I have one of two issues.

1) Temp sensor is bad. PN is: 3852029 and they go for about $20...does anyone know what generic Ford part will work? There seem to be a few different ones from the 1994 time that went into V8/V6 engines.
2) Temp gage is bad in the dash...suspect too since these dash gages are knowingly unreliable.

My plan is to pickup a new sensor and anther external temp gage so I can be sure I am getting the correct engine temp.

Will report back.