1994 omc 3.0l circulation hose

[Tpmac68]

Hello, I have 1994 Four Winns with a 3.0l omc in it. It was overheating and I replaced the obvious failed items. (T-stat, impeller, circulation pump due to leaks at the shaft and the burnt flapper valve) it doesn't overheat now but the large horse shoe shaped hose at the circulation pump swells up real bad under cruise/load. It retracts a bit and swells again every time the t-stat opens and closes. The only thing I haven't checked is the power steering cooler. Is there anything else I might be missing?
Tim

 

[alldodge]

Hello, I have 1994 Four Winns with a 3.0l omc in it. It was overheating and I replaced the obvious failed items. (T-stat, impeller, circulation pump due to leaks at the shaft and the burnt flapper valve) it doesn't overheat now but the large horse shoe shaped hose at the circulation pump swells up real bad under cruise/load. It retracts a bit and swells again every time the t-stat opens and closes. The only thing I haven't checked is the power steering cooler. Is there anything else I might be missing?
Tim

Howdy Tim

Sounds like you just need to replace the hose before it burst. The hose is getting weak and can rupture at any time.

 

[Tpmac68]

Sorry, I forgot to mention I replaced that hose as well, thinking the same thing. First time out after replacing it the new hose swelled up and blew off of the pump. Also forgot to mention (for testing purposes only) the flapper valve is removed and the restricter plate is removed at the exhaust riser. My impeller was in good shape, but found prices of an old impeller in the t/stat housing. I inspected and cleaned out what hoses I could, except the steering cooler.

 

[Tpmac68]

I had the boat out yesterday, the hose stayed on but still swelled up. The river temp was about 58 degrees, the engine temp stayed consistent between 150-170 degrees at 4500 rpms.

 

[alldodge]

The hose actually shouldn't expand with the thermostat open or closed. With a new hose then the next thing I would check into was the exhaust system. Your manifold, elbow or even the drive may have a restriction. Running up to 170 in 58 degree water with a 140 thermostat leans me toward there is a restriction somewhere. You should be running no more then 160 when running hard.

Look where the exhaust pipe mates to the drive, something may have fallen into this area and is blocking water flow

 

[Tpmac68]

I pulled the boot that connects exhaust to out drive and that is where I found the melted flapper valve it was intact and after getting it out of there I stuck my shop vac. down the exhaust to clean any other debris out before putting it together. Other than the out drive, steering cooler and exhaust/intake manifold I've had everything off the engine and inspected what passages I could. I'm not familiar with this out drive, but should water come out the prop or should that just be exhaust? Warm water comes out the rear of the out drive and exhaust comes out the Prop right now.

 

[alldodge]

At idle and on the muffs you will see most water come out the drive, when in the water and at speed the water/exhaust comes out both prop hub and drive.

Since you have cleared the exhaust tube and drive area the next place would be the manifold and elbow. Does the hose expand when at idle on the muffs?

 

[Tpmac68]

The hose doesn't expand at idle or even off idle with the muffs on. No water was coming out the prop hub, just the drive. As far as the temp it just fluctuates mildly just above and below 160 it's just a gauge so actual engine temp is tough to know. It runs great on the river with no issues other than the hose blowing up like a balloon before the t/stat opens. With your comments on the water flow I'm guessing now there is a restriction in my lower unit. Was kinda hoping I didn't have to go there, but it's just another box of bolts and my time. I'm gonna run it again with muffs this morning to confirm the water flow again, prior to tear down. Thank you, I will update results as I get them.

 

[alldodge]

As before there should be no difference in pressure when the thermostat (TS) is open or closed. Once the block fills with water and the TS is closed water just passes by and out the exhaust. When the TS opens cold water flows in pushing hot out. Your problem might just be in your TS housing.

Check how the TS and the pieces are mounted correctly

 

[Tpmac68]

No Title

My cooling system at the t/stat is a bit different. The temp sensor is in the location for the hose labeled "13" the bypass hose is on the other side of the housing with a brass "T" that runs to the riser elbow and the brass "T" I bought the boat about a month ago this way and have been tinkering since then. I believe it would have the same effect, but just wanted to provide as much info as possible. It is a 3.0l GS motor if that matters.

 

[alldodge]

There are so many GS models would need to have the rest of the letters to get exact. Either way the flow should be the same, and I'm thinking more it may be the TS or something in the housing. Found the link below which is one of the GS models

http://www.volvopentastore.com/Circ...on_id.301593889--store_id.366--view_id.767633

 

[alldodge]

You know we might want to go back to the hose. The hose should not blow up like a balloon, if it does even though its new, this should not happen

 

[Tpmac68]

I agree going back to the hose thing, but since it happened with the old hose it has me confused. Eng model # is 302CCPMDA. I didn't get a chance to run it today to test things. Heck the way it's acting, it seems like if I left the t/stat out it would be fine, but that's not right and not how it was designed.

 

[bruceb58]

You likely have a restriction in your thermostat housing exit to your exhaust manifold or the manifold itself. Salt water boat?

 

[alldodge]

Found another pic from the model number. The hole allows water to pass and exit when the TS is closed. When closed this is a restriction but should not be enough to effect the hose, the hose should not balloon

 

[Tpmac68]

Thank you, that pic is more consistent with my system. That port was plugged solid, but I cleaned it out when I replaced the T/stat. I'm going to check out the hose and port wear it goes into the manifold a little closer.

 

[Tpmac68]

Bruce, it is an as far as I now always has been in fresh water. It doesn't show any signs on out drive or trailer that it's ever been in or around salt water.