2000 5.7 gsi pwtr possibly overheat gremlin.

SD2600

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So last year i repowered. 5.7 psi pwtr. I was unable to make any trips as i have been chasing an overheat per my gauge.

Things I've done. I have replaced every hose. New Thermostat. sea water pump. New threw transom fitting. new outdrive hoses. VP sx-M. New seals in the lower.

I installed clear hoses on the sea water pump to look for air bubbles. bubbles are present.

I thought it might just be my temp gage and sender so i installed a new gage sender and wire.. no change

My temps running on the muffs hang at 160-165 then for no reason the gauge climbs to 180-190.. if i put it in neutral and increase the throttle to 1100 rpm for a few secconds, temps will fall to 150.

I shoot the top of the thermostat housing with a temp gun and its about 120.
The intake manifold closest to the temp sender is 112-115

My port riser is about 98. my starboard riser is 125. taken on the top.

My risers have always varied in temp.. both are brand new.

Im stumped, My temp gun readings on the motor indicate im not to hot but the gauge says hey dummy don't cook your new motor..

Any thoughts are greatly appreciated..
 

alldodge

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I installed clear hoses on the sea water pump to look for air bubbles. bubbles are present.

Your sucking air, this would be my guess as to the problem
 

aimlow

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Does the new t'stat have a hole in the flange for water to bypass?
 

SD2600

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Your sucking air, this would be my guess as to the problem

I agree... but where? I just installed brand new hoses today from the transom fitting to the p/s cooler. And from the p/s cooler to the sea water pump this am.. hoses fit very snug with clamps tightened down...
 

Scott Danforth

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did you replace the hose fitting on the drive itself? check that, because for years VP had issues with that fitting
 

Lou C

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Plastic fitting in the pivot housing. Just like the OMC Cobra.
 

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Scott Danforth

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Lou, they were not always plastic. for years VP used a white metal that would disappear after a few years.
 

Lou C

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the SX series I think always had the plastic one (as they just adapted the OMC transom design) the aq had the metal one that corroded correct?
The plastic ones can crack if water gets trapped in there. Then air can get sucked into the water flow.
 

SD2600

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Plastic fitting in the pivot housing. Just like the OMC Cobra.

Yes I replaced that fitting, it is plastic. I also replaced the hose from that fitting to the thru metal transom fitting. I also pulled the lower and replaced the two rubber seals....

lou I read your suggestion about hooking up the muffs and pouring water from the motor side while someone watches for leaks in the drive.. haven’t tried that but might give it a go today
 

Lou C

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I bet you have seen this but if not google "Volvo Penta Overheat Diagnosis" Its a PDF document.
it tells you how to tell if air is being sucked in anywhere in the cooling system, and also how to determine if an overheat might be due to leaky head gaskets. I know you have a new engine but this is still worth checking for.
 

SD2600

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yes lou, i do have a copy. I believe im sucking air somewhere before my impeller but where? My p/s cooler is clear of any debris, all hoses are brand new and secured tightly.

Would it be recommended to pull the hoses and apply a layer of some type of sealant to aid in the connections being air tight?

Is it possible my new gauge and temp sender are playing tricks on me as the temps on the thermostat, intake, and risers are really not very hot?
 

aimlow

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I don’t recall.. it’s a factory replacement I believe 160 degree ... should I pull to check?

The SMALL bypass hole keeps the t'stat wax pellet always in consistent temperature coolant, and often eliminates wild temperature flucuations. Make sure the hole isn't covered by the gasket.
 

Lou C

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The way the V/P thermostat is retained in the housing (same exact part as OMC's) is with a rubber ring that holds the thermostat from underneath into the 'stat housing. No way it can block anything.
I wonder if your impeller housing can be sucking in air via a defective seal? When you checked for air bubbles, where did you put the clear hose? Before or after the impeller housing? If you install the clear hose between the P/S cooler and the impeller housing, this will tell you if there are any leaks between the lower unit and the housing (ie water transfer grommets in the drive, plastic fitting in the pivot housing transom hoses etc). If no bubbles then good. Now, put the clear hose between the outlet of the impeller housing and the thermostat housing, if you get bubbles then, that would cast doubt on the impeller housing seal. Might be worth a re-check to narrow it down.
 

SD2600

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Lou I currently have clear hoses attached to the inlet of the impeller and on the impeller of the housing...

im getting bubbles on the inlet and the outlet

i assume bubbles in means bubbles out

i will try to narrow it down this afternoon and get back with any findings
 

Lou C

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yep bubbles in means bubbles out, you might want to do the other test I mentioned (was on the Striper board) where you disconnect your impeller feed hose at the impeller. You can tape over your out drive water intakes to seal em up. Move the drive to the starboard side so you can see into where the pivot to transom mount hose is and have someone hold that hose up and fill it with water from a funnel while you look at all the leak point possibilities. An even better way might be this: get some no tox Sierra antifreeze, mix up a 50/50 batch, and use that instead of water. It is bright green like the old style antifreeze (but non toxic) and will show up better than water. Might need a bright LED flash light and a mechanic's inspection mirror. The reason why Volvos and Bravos are more prone to this issue is the impeller must pull water all the way from the drive water intakes to the impeller housing, there are a number of points where you can pull in air. On a Merc Alpha or OMC Cobra, that same path is under pressure, the water is pushed forward so leaks will be more obvious.
 

SD2600

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ok. i taped off the inlet holes on the outdrive. I removed the hose that goes from the power steering cooler to the thru transom fitting. I inserted my garden hose and dribbled H20 until it was almost full. I then jumped down to inspect the connections on the outdrive as per lou's instructions... I found h20 coming out what looks to be in the area of the plastic fitting #18

https://www.marinepartseurope.com/en...-44-10147.aspx

i was unable to pull the drive as my time was limited.. This part was replaced new as i have been trying to track down the air issue.. Perhaps I may have cracked it when tightening it down... If time permits i will pull the drive tomorrow and inspect...

more to follow.

Thanks for the input guys
 

BRICH1260

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If it is damaged obviously replace it. Either way coat the threads with drive grease to help it seal better. Plus it will make it easier to remove next time.
 
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