Volvo 5.7 Gi-A Overheat

[gverb1219]

OK, so hear it goes.

What it is.........

2002 Volvo Penta 5.7 Gi-A, ser# 4012059922 VP# 3869117, Closed Cooling system.

What it's doing....

Overheating AFTER coming off plane. Can run for hours at 3200 rpm...........slow down and within 30 to 40 seconds temp rises and alarm sounds. Overheated coolant flows out of overflow tank.

What I've done so far.....past to present...

10 months ago......

Overheating issue....exhaust bubbles in coolant tank......found bad head gasket.......had heads/valves done, new head gaskets, intake gaskets, etc....both sides


8 months ago.....

Overheating again....brand new manifolds, risers, installed new metal VP gaskets according to VP service bulletin.


Seemed to run ok......



Overheat again.......

Replaced cracked plastic hose connector between outdrive and transom shield that was allowing air intrusion...

Seemed to run ok......


Overheating again.....

Replaced expansion tank cap.....

Seemed to run ok......



Overheating again....

Replaced thermostat.....


Seemed to run ok......



After a few outings now AGAIN overheats ....this time AFTER coming off plane.......

Removed and tested expansion tank...no leaks, good pressure, good water flow.....

Removed and replaced engine coolant circulator pump.......

Installed clear reinforced hoses on raw water pump according to the VP Overheat Pamphlet posted by Don (RIP)
NO Air Intrusion found.

Pulled suction side hose off RWP....it sucks....
Pulled outlet side hose off RWP at expansion tank fitting.........water flows good....more flow with increased rpms
Pulled RW hose off expansion tank to exhaust manifolds.......water flows good....more flow with increased rpms

Backflushed all hoses..........all clear
Backflushed hoses from exhaust manifolds.......through expansion tank.......water flows good dumping from outdrive.......
Removed/replaced raw water pump impeller anyway.....(piece of mind)

I have about replaced everything on this engine related to "cooling"...........yet it still overheats.........

I can run it for hours and the temp gauge stays in the 170*-180* range (closed coolant calls for a 170*t-stat), but as soon as I slow down for the no wake zone, or slow when I get to my destination.............temp climbs to 200*+, alarm goes off, coolant overflows from tank.....

I am completely baffled..............as are the mechanics I have been in contact with..........




Now, for something I thought interesting............

Just yesterday I spoke with a service guy who was on the phone with a "certified Volvo-Penta mechanic".
He asked me what kind of manifolds did I use when I replaced them?

I said I used Volvo risers and GLM manifolds from Sierra....I got the risers brand new at a great cost from a wholesaler........but they didn't have manifolds so I got the GLM's because of the HIGH price of VP manifolds.....

He said........"That's your problem"



REALLY.?????????



If ANYONE can help I'd REALLY appreciate it................I'm at my wits end here............

 

[Safisher71]

Re: Volvo 5.7 Gi-A Overheat

Hi

Have you checked the closed system fresh water impellar?
At high speed it may be generating sufficient flow around your block and through the heat exchanger, but when you slow down the pumping efficiency of the impellar falls and flow to the heat exchanger is reduced, thereby causing overheating at slow speed. Could be an airlock in the closed system fresh water side.

Also check the temperature with your hands of the raw water entering and exiting the heat exchanger. If the temperature is about the same then the raw water flow through the exchanger is good. If it is cold entering and very hot exiting, then the residency time in the exchanger is too long due to low raw water flow or back pressure from your manifolds.

Hope this helps
Keep us informed.

Cheers

 

[dypcdiver]

Re: Volvo 5.7 Gi-A Overheat

Interesting one. You seem to have most things covered, so just grasping at straws here. You say you have flow of the raw water out of the heat exchanger, which leads me to think that there might be a restriction in the manifold/riser, that only an increased flow can overcome. Points I'd check 1. Make sure the 90 deg elbows that carry the raw water into the manifolds are clear and the hole into the manifold is at least 1/2". 2. The metal gasket riser/manifold is the one with 4 slots.(they did a restricted one with only 1 slot) 3. Make sure the rubber joining hose between Riser and exhaust down pipe is seated properly as I have seen a hose clip fitted in the wrong place restricting flow through the annulus. 4. Make sure you have the correct impeller in the raw water pump it should have one with VP 3862465 moulded into the centre boss or the last one I got had, it came as a kit 21213664.

Best of luck.

 

[gverb1219]

Re: Volvo 5.7 Gi-A Overheat

Thanks guys.......

Hi

Have you checked the closed system fresh water impellar?


Keep us informed.

Cheers

Circulator pump for engine coolant is brand new, so I don't think that is it. When I pulled the thermostat....I started the engine briefly and coolant flow in engine is good.
Raw water hose entering heat exchanger is cool to the touch. Hose leaving heat exchanger is pretty warm....not hot, but pretty warm.

1. Make sure the 90 deg elbows that carry the raw water into the manifolds are clear and the hole into the manifold is at least 1/2". 2. The metal gasket riser/manifold is the one with 4 slots.(they did a restricted one with only 1 slot) 3. Make sure the rubber joining hose between Riser and exhaust down pipe is seated properly as I have seen a hose clip fitted in the wrong place restricting flow through the annulus. 4. Make sure you have the correct impeller in the raw water pump it should have one with VP 3862465 moulded into the centre boss or the last one I got had, it came as a kit 21213664.

Best of luck.

Manifold elbows are new and clear and are 3/4". I put water hose to manifold elbows and water seems to flow unrestricted out exhaust.
The new riser gaskets have 4 slots to match the manifold and riser slots.
I haven't checked the exhaust hose, but will check it. I don't think it is restricting flow.
Yes....I have the correct impeller installed. Water flow from heat exchanger appears to be pretty good. There is no air intrusion and water flows from expansion tank hoses very good.......

I am puzzled to say the least.....

I may pull manifolds even though they are brand new. Seems I have had overheating issues ever since I replaced the bad ones............

Don't know what else to try.......