Overheating Volvo 3.0GS with SX drive

[CayugaCobalt]

My 2001 Glastron SX175 has a 3.0GS Volvo that was overheating last summer, usually after about 20 minutes at 3500 rpm cruising. This spring I replaced the raw water impeller, and I replaced the thermostat. I found bits of the old impeller in areas upstream of the thermostat and removed them.

The boat was perfect the first 3 times out, but then once again, after maybe twenty minutes at 3200 rpm on plane, it overheats, out in the middle of the lake for no apparent reason.

I had read that these on-plane overheats could be from a corroded water tube in drive unit, so had water tube and baffles replaced last weekend.

At the time, mechanic said re-circ pump was leaking, so replaced recirc pump also. Now have new raw water impeller, thermostat, re-circ pump and water tube.

Now boat overheats after 15 minutes on plane. You can let it cool and then drive home at low speed without incidence.

So it seems to be a heavy volume/flow type problem. Any ideas where to look for blockage.

Anybody been in this same situation?

 

[bruceb58]

Re: Overheating Volvo 3.0GS with SX drive

You need to check to see if you are sucking air. Put a clear peice of hose in going to the water pump.

Have you had the drive off? Was the oblong O-ring replaced when the drive was repaced for the water passage? There is another o-ring for where the rubber hose connects to the tilt housing that may need replacing.

 

[Steev-oh]

Re: Overheating Volvo 3.0GS with SX drive

I had the same issue and replace all the same parts even a new water pump.
I ended up finding the problem when I had my muffs on and the engine wasn't running I had water flying out of my inline oil cooler. When I removed the oil cooler I found it split half way around, it is copper so i solder it back up and it is as good as new. I never would have found the problem if i did't have the engine off and the muffs on with the water flowing.

Might be a good place for you to check, could be the same thing.

my boat is a 97 fourwinns 180h with a 4.3gl/sx not sure if the oil cooler would be the same or not but worth checking

 

[Don S]

Re: Overheating Volvo 3.0GS with SX drive

Download this Overheat diagnosis file. It will help you locate your problem.

http://www.4shared.com/file/50572185/e88f1d89/Volvo_Penta_Overheat_Diagnosis.html

 

[CayugaCobalt]

Re: Overheating Volvo 3.0GS with SX drive

Thanks guys, seems like the consensus is sucking air on plane. I told the marina this was my hypothesis and had them change the water tube, which was foolish, since it is stainless, not copper, but the marina mechanics are not smart enough to do anything but replace parts, so they replaced my brand new raw water impeller and sold me a new recirc pump, since it was leaking.

Is the consensus that a piece of rubber impeller blade stuck somewhere is not the problem?

Thanks

 

[CayugaCobalt]

Re: Overheating Volvo 3.0GS with SX drive

Yes the drive was off when they replaced water tube and bellows. They did not replace anything else.

 

[CayugaCobalt]

Re: Overheating Volvo 3.0GS with SX drive

Guys thanks for your input; FYI installed clear vinyl tubing, no air bubbles so not sucking air. Must be restriction to high volume flow.

I am going to pursue Steve Ohs thought and go after the oil cooler.

Any telltale signs when this steering oil cooler is bad in addition to overheating?

My cooler is 10 years old and I can imagine it has corroded out.

Thanks again

 

[CayugaCobalt]

Re: Overheating Volvo 3.0GS with SX drive

Update, 7/20/10, checked the oil cooler , nothing wrong there. Could see clearly thru it, no rust or dirt in it.

So I am left with no clue why I cannot keep the block cool when on plane at 3200 rpm for more than 10-15 minutes.

New water tube, new impeller, new thermostat, new recirc pump and boat holds temp perfect at low rpms forever, but once you get going at speed, too hot.

 

[redneck_cdn]

Re: Overheating Volvo 3.0GS with SX drive

Sounds like there may still be some remnants of the old impeller restricting cooling water flow in the thermostat controlled cooling loop.

Does the exhaust manifold get over heated as well or just the engine circuit?

Try to flush the lines out in both directions to remove any potential blockage.

Compression check on the cylinders?


Alex
96 Four Winns Horizon
3.0 GS OMC/VP Sx

 

[CayugaCobalt]

Re: Overheating Volvo 3.0GS with SX drive

ALex, I did remove all the broken impeller parts I could find and double checked for them again recently.

The exhaust manifold is getting hot, so does that indicate "clogged" riser or more an indication of blown head gasket???

 

[CayugaCobalt]

Re: Overheating Volvo 3.0GS with SX drive

By the way, the boat is a 2001, engine is model year 2000. I have had the boat for 3 years on Greenwood Lake in NJ. It had 83 hrs on it when I bought it and now it has like 165 hrs on it.

 

[CayugaCobalt]

Re: Overheating Volvo 3.0GS with SX drive

Here is another clue, the engine does not cool off if I immediately decelerate down to a stop.

I can watch the temp gauge while driving down the lake at 3200 rpms and the temp will be 170F and suddenly in like 5 seconds it is 200F, I immediately decelerate, go to neutral, and it does not immediately cool off or respond.

Generally I get impatient/nervous that it is not cooling off, so I turn engine off.

If the head gasket were leaking exhaust into the water, wouldnt the engine cool with lower rpms, becuase of less exhaust? Furthermore, since the boat holds 170F perfect at low speed doesnt this eliminate the head gasket hypothesis entirely?

 

[CayugaCobalt]

Re: Overheating Volvo 3.0GS with SX drive

Solution found! CLogged exhaust riser. Cost only one hour labor and a $7 gasket, why the hell the mechanic would not do this first instead of last.

This problem started last year and was a combination of faliing old raw water impeller and clogged riser.

The mechanic replaced the one hole riser gasket with an in stock mercruiser 4 hole gasket, so not sure what the long term implications of that are.

Thanks to Don and sTEVE OH and everyone for helping.