Volvo 5.7 overheating

Sea Amigo · Oct 12, 2009

I finally have the engine running great after having fuel and ignition problems were overcome. Now it's overheating when I apply power. At first start the engine comes up to temperature slowly and stays in the normal range (180 - 200 deg) until I apply power. Then it starts to rise slowly for about 15 minutes until it looks like it's going to overheat and I throttle back. I keep it a few RPMs above idle idle for a bit while it cools down. Then I try again only this time it overheats after 5 minutes at power.

I checked the impeller, back flushed the oil cooler, lines and outdrive intake. Pulled the plugs out of the backside of the manifold and flushed out the crud. All with same result. Ideas please.

Maclin · Oct 12, 2009

Re: Volvo 5.7 overheating

What year and model# ?

The risers could be corroded and restricting water flow.

You do need to verify that water is getting to the raw water pump and on thru the engine with no problems, air bubbles, etc. Different year Volvos have different problems in that regard.

Don S · Oct 12, 2009

Re: Volvo 5.7 overheating

At first start the engine comes up to temperature slowly and stays in the normal range (180 - 200 deg)

That is not NORMAL
You say you checked the impeller. Would you know a good one from a bad one? Did all the vanes straighten out after you removed it from the pump? If not, you need a new impeller.
Are the bearings in the pump smooth? if rough at all, that means the bearing are shot, probably because the seal is shot allowing water to leak into the bearings, and allowing air to be sucked into the pump. That causes overheat.

havasuboatman · Oct 12, 2009

Re: Volvo 5.7 overheating

I am not an expert on volvo's, but 180- 200 seems kinda high for the operating temp.
Maclin has you started in the right direction. Check for obstructions in the freshwater cooling system. especially at the oil coolers. Have you replaced the impeller recently? Was it damaged? did you get all of the pieces out?

carlfarey · Oct 13, 2009

Re: Volvo 5.7 overheating

just had the exact same problem, it was my Risers, get them done before it causes more damage. I left mine too long and had some real problems because of it.

Carl.

Sea Amigo · Oct 13, 2009

Re: Volvo 5.7 overheating

its a 1993 572A (GM 350 2bbl) raw water cooling. The manifolds and risers were replaced in Apr 07. The sea water pump was replaced in Oct 07.

I plan on taking the risers and manifolds off and checking them for blocked passages first.

I wouldn't think they would be rusted our bad enough in two years worth of running. I do flush with fresh water after each use.

Any other thoughts?

Maclin · Oct 13, 2009

Re: Volvo 5.7 overheating

Certainly running in salt water makes the corrosion cycle quicken many times over. Flushing with fresh water is good but I think using salt-away keeps the corrosion cylce from getting out of hand. Good luck on your efforts.

mikeneal · Oct 14, 2009

Re: Volvo 5.7 overheating

Could be an air leak, sometimes the plastic fitting where water tube goes thru transom shield cracks. Something is wrong, 200 is too hot.

Sea Amigo · Oct 17, 2009

Re: Volvo 5.7 overheating

Took the risers and manifolds off and found r/h clogged up about 70% and l/h about 50% with lots of black, hard, sooty material. There was not an excessive amount of rust or scaling. Cleaned them out with a drill motor and a long tear drop rotary file. Checked for leaks using acetone. Cleaned off the mating surfaces of the risers and manifolds. replaced the gaskets and assembled everything back with Permatex. i hate the stuff but it does work wonders. The water flow out the exhaust, compared to before, is incredible . I was only able to try it with the hose attached but it barely got over 100deg. Plan on trying it out on the water tomorrow.

bruceb58 · Oct 17, 2009

Re: Volvo 5.7 overheating

Did you put in new riser gaskets? You should also put these on dry with no sealant. Did you check the flatness of the riser manifold junction? Also, you need at least 1/4" material between the exhaust area and the water passage on both the manifolds and the risers. If these are ore corroded than that, you need noew risers/manifolds.

Are the manifolds/risers that you replaced in 07 OEM manifolds/risers?

Sea Amigo · Oct 18, 2009

Re: Volvo 5.7 overheating

New riser and manifold gaskets. I did put the risers on with permatex. I've used that stuff on airplanes for 30 years and found that it works until something else breaks. I wanted to make sure that no water would get back into the exhaust at that joint. I had plenty of material left in between the passages and I did check the flatness of the mating surfaces, after cleaning them up. I then polished up the surfaces with a scotch brite rotary wheel and they looked great. Everything went on with a troque wrench to mfg specs. Manifolds and risers are Osco not OEM.

Lets see what happens.

mikeneal · Oct 18, 2009

Re: Volvo 5.7 overheating

I would suggest you replace the risers ASAP, if they fail it takes the motor out and if they had that much scale they are close to the end.

bruceb58 · Oct 18, 2009

Re: Volvo 5.7 overheating

I would agree with Mike.

Sea Amigo · Oct 18, 2009

Re: Volvo 5.7 overheating

Risers were not clogged with scale or rust but some hard sooty like substance. Also found the old riser gaskets with two of the six ports not cut out and blocked. I don't think the risers are that bad.

Also I did go and do a sea rial. Alas no joy!. It was much better, taking longer to reach 200 deg. but it eventually did. Today the engine started normal and ran great. Idled fine for 15 min out to the channel. Temp stayed at 130deg. Accelerated and saw the temp climb up slowly to just past 200 in about 20 minutes of running. I then pulled back and let it cool before returning home. On idle back to dock the temp came back down to 175deg but slowly. Took about 15 minutes to get down to that. I put the muffs on to flush and it cooled down more to about 150.
So to recap, VOLVO 572a (GM350 2 bbl) new plugs, ignition module, rebuilt carb, ignition timing dead on at 8 deg BTC per the manual, good seawater pump impeller on a 2 yr old pump, 2 yr old riser and manifold passages are not blocked, back flushed line to seawater pump intake to clean out oil cooler, checked intake hose clamps, pulled engine block drain plugs to check for sediment and found none, Have lots of water coming out both exhaust hoses at bottom of transom shield.

What am I missing?

Thanks to all for your input. It has helped a lot.

capitan72 · Oct 18, 2009

Re: Volvo 5.7 overheating

Make sure you choose your impeller by checking the model number of the pump. I made the mistake of replacing mine with the same one that was in there to start. Turns out the guy before me put the wrong one in. I was pulling my hair out for a week trying to figure it out.

user64 · Oct 20, 2009

Re: Volvo 5.7 overheating

"What am I missing?

Thermostat? Circulating pump?

Sea Amigo · Oct 24, 2009

Re: Volvo 5.7 overheating

Going to replace impeller on sea water pump tomorrow, just in case. Also replacing t-stat. Will report what happens.

carlfarey · Oct 25, 2009

Re: Volvo 5.7 overheating

Good idea, I did all of those as well.

Carl.

Sea Amigo · Oct 25, 2009

Re: Volvo 5.7 overheating

New impeller, and thermostat didn't do it. The only thing left is the engine circulating pump. It turns freely and doesn't make any noise. I'm thinking it could be plugged or the impeller is just worn out on it.

I did check the risers when the engine was getting hot and they were cool enough for me to put my hand on them and not get burned. The raw water pump is definitely pumping water. It's just not cooling the engine.

Anyone have similar problems due to the circulation pump?

Robertpel9 · Oct 26, 2009

Re: Volvo 5.7 overheating

you may be sucking air and it could be happening even in the outdrive. I had a similar problem (search my threads). Hook up clear hoses to the water pump inlet and outlet and look for air bubbles. If you have them then theres your problem. You will se a link to a volvo overheating troubleshooting guide in my thread on this tops that Don S posted

Good luck

Volvo 5.7 overheating

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