volvo 4.3 engine temp fluctuations

[harmonicat]

Hi all. Just bought a 2005 glastron sx with a Volvo 4.3 GL-D I can idle all day(on the water) and the engine temp stays at 155 degrees but at any other speed above idle the temp gauge starts climbing to 185 then quickly drops to 155. This climb/fall pattern happens continuously. Any ideas where to start to remedy this problem? Thanks.

 

[Bondo]

Re: volvo 4.3 engine temp fluctuations

Ayuh,.... Welcome Aboard,.... It's the T-stat openin', 'n closin',....

Nothin' to fix, as it's expected,...

 

[Don S]

Re: volvo 4.3 engine temp fluctuations

Sounds like the stat is sticky and opens and closes all or none.

Try replacing it with an OEM stat and see if it smooths out. Should level out around 175?.

 

[harmonicat]

Re: volvo 4.3 engine temp fluctuations

Thanks for your help. If it is a sticky thermostat, would the eng. temp. not climb and fall at idle speed as well? Will replace it tomorrow and post results.

 

[harmonicat]

Re: volvo 4.3 engine temp fluctuations

Dealer doesn't have the part so I have to wait 2 days. Anyone else with a 4.3 out there? What are your normal op temps? Does yours fluctuate? or hold steady at a certain temp?

 

[rbuljo]

Re: volvo 4.3 engine temp fluctuations

I have an 4.3GXI-B raw water cooled, rock steady at 140F..

 

[harmonicat]

Re: volvo 4.3 engine temp fluctuations

Thanks....I pulled the old thermostat out and tested it on the stove while suspended in a pot of water. Thermo is stamped 150 degrees. Its an oem thermostat that book says is 160 degrees. It didn't start opening up until 155 and was not fully opened until 175 degrees. it did open gradually and not all at once like it was sticking. Does this sound like it's defective? If it is, I'm wondering if that would cause the problems I described above in my first post?? stuck my finger inside the intake and the water ports don't seem clogged at all. Thermostat housing was in great shape inside too. I'm going to try flushing the risers first and then put the new thermostat in the engine.............risers flushed ok. the garden hose didn't fly out of oem hose because of poor flow or back pressure(clogged riser)..water came out exhaust nice and clean. Everything is back together will take it to lake tomorrow to try it out and post results after.

 

[harmonicat]

Re: volvo 4.3 engine temp fluctuations

Life and weather got in the way but I just came back from the lake today. It's still the same, no change. At idle it stayed at 150 but anything over 1200rpm it would climb and fall. Flushed everything out again before we went. I guess I'll get some gaskets and pull the risers this week to inspect them. I did buy a infrared thermometer though and the gauge checks out good. It was doing some strange poping sounds though above 3000rpm and you could feel a slight loss of power. Still have the same gas as when I bought it this spring though which sat in the tank all winter(about .25 to .5 of tank) maybe I'll change the spin on fuel filter as well. Couldn't get it to do the pop sound again after the first few times though. Still searching, will keep this thread updated Oil on dipstick looks good also, not milky from water mixing with it. Pulled out some oil via the dipstick tube. Its dirtier from bottom of pan but no water so that's good.

 

[harmonicat]

Re: volvo 4.3 engine temp fluctuations

put lots of fresh gas in and no more popping sound at higher rpm but temp readings have changed slightly......cools to 145 then up to 180 before rapidly dropping and now it does it at idle. a slower version than at high rpm. Getting ready to pull risers to check and decided to pull impeller first(guy I bought it from said it was new...ya right) anyway found two cracked vanes(picture attached) Could this be my temp rise/fall problem? Would those two cracked vanes cause cavitation or something enough to give these symptoms??? Thanks guys!

 

[Don S]

Re: volvo 4.3 engine temp fluctuations

Fix it and find out. It's no good that way.

 

[harmonicat]

Re: volvo 4.3 engine temp fluctuations

Impeller is in and I just tested it on the trailer with the flush out fitting. Had it at 1600 rpm and Temp still rises and falls but not as fast(wishful thinking maybe). It also didn't get quite as hot(175 as opposed to 180) before temp started to drop. Confirmed all this with infrared gun. I don't know, maybe I'm chasing a non existent problem. Just bought this boat so I don't know what normal is. Others say that their temp stays steady. It seems to me that temp should hold steady once thermostat opens. But I'm a greenhorn so what do I know. But pressure came from something causing the large hose to burst the first time I had it out. Between circ. pump and thermostat housing. Will try at the lake again tomorrow. Risers held a steady temp around 95-100 so i'm not going to pull those yet. Oil level and color has not changed.

 

[Don S]

Re: volvo 4.3 engine temp fluctuations

Put it in the water and see what it does.

 

[aerobat]

Re: volvo 4.3 engine temp fluctuations

anybody gave a thought he might have a defective gauge or sensor ??

 

[harmonicat]

Re: volvo 4.3 engine temp fluctuations

Thanks for the input but I verified the gauge/sensor with an infrared temp gun. They seem to be working accurately.

 

[harmonicat]

Re: volvo 4.3 engine temp fluctuations

Well, I think I found something. Not sure if this is the cause of the problem though. Pulled the risers and one looked good the other had a touch of rust down in the exhaust manifold and some rust spots in the riser exhaust part. Pictures attached. The first time I put boat in the water it started and ran fine but 100 feet from the dock it stalled and was hard to start like it was starving for fuel. After lots of pumping and cranking it fired back up again....I think It backfired a few times during this too. then when I opened the engine compartment I noticed the burst hose as described in previous post(this thread). The riser that was always hotter is the same side as the picture with the small amount of rust. Also, previously when I pulled the plugs the front plug of the engine(rusty riser side) had maybe a spot of rust on the side electrode tip. It wiped right off with my finger but it was definitely rust coloured. I have the new metal riser gaskets and am waiting to hear from dealer to see which way the ridges go...up or down? also off to c tire to get some permatex copper sealant. Luckily I found on this site the service bulletin about using the sealer. Dealer just called and said ridges go up towards riser. He had no idea about a service bulletin. If the gasket did fail, maybe some exhaust was going into the cooling system and causing an air bubble at thermostat giving me the temp fluctuation. Hope that's it. everything is buttoned back up and I'm waiting until tomorrow afternoon to try it out.

 

[harmonicat]

Re: volvo 4.3 engine temp fluctuations

Turns out I used the wrong sealant and had to redo my work but I'm glad I did because upon further inspection of those black spots on the metal mating surfaces of riser and manifold that wouldn't come off were actually small corrosion spots filled with a carbon type stuff? Used a dental pick to remove it and then ended up with small pits. I also found a very low spot right where it looked like the water had come in. Spent the last 4 hours block sanding both surfaces until they were flat and there were no more low spots , just shiny metal. But it's back on and ready for a test tomorrow. Will post the results in next day or two.

 

[harmonicat]

Re: volvo 4.3 engine temp fluctuations

Well, I tried. I was careful block sanding but not careful enough I guess. Started it up and a stream of water about 1/8 inch was squirting out at gasket (btwn riser/manifold) right in the front on port side. Other side was good. Shut it down immediately and pulled the plugs. There was no water(no water in exhaust manifold either)but just in case, I sprayed inside plug holes with WD. Within 45 min. I had both risers and manifolds sitting on my bench ready to take to machinist tomorrow morning. I'm debating taking the plunge and buying a new set because the machinist might be more wasted money. Does anybody know if those 4 long bolts holding the riser down ever stretch and need replacing? I tightened them down to 29lb but they didn't seem that tight when I removed them. Are those ridges on the metal riser gasket supposed to crush or flatten when torqued down? Mine didn't at all really.

 

[harmonicat]

Re: volvo 4.3 engine temp fluctuations

Got the risers and manifolds back and still had three hours sanding to do after reading the specs in the gasket install sheet. Steep learning curve here. Anyway they are within specs and back together. Just test ran it and temp now only climbs to 170 before it drops to 150. Still drops on the quick side but it takes twice as long to go up from 150 to 170. Not much else I can do. New plugs. new impeller. riser gaskets. backflushed everything and every hose. Oil level still the same and nice and clean. I guess this is normal for this engine. I'm going to get another thermostat from a different supplier this weekend just to try it.

 

[Tail_Gunner]

Re: volvo 4.3 engine temp fluctuations

Ok for future refrence here's a solution. Go to ace hardware get a product called wood bleach. mix it up and let any part you have soak in submerged solution...all the rust will be gone and it will cost you about 8 dollars

oxalic acid

 

[harmonicat]

Re: volvo 4.3 engine temp fluctuations

I'll give that a try, thanks. Are you thinking my manifold/riser passages might be corroded/clogged?