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over heating issue

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biggs7

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hey guys new guy sorry. 96 chase, 5.8L inboard. i just bought it and discovered the plugs in the block were out and a frost plug missing. Put it all back together and it over heats. No leaks inside the engine compartment, oil is fine. I put die in the coolant to see if it was pumping out of the leg but it will not overheat sitting on the lawn with the dog ear on. The water existing the boat is warm. Opinion is the impellor shot? I took it out but the impelor looks good, but the boat has sat for two years. any suggestions on what to look for? I have a pressure tester and will see if it is a head gasket but I think it is the heat transfer system. Appreciate any help. Chad
 
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biggs7 said:
hey guys new guy sorry. 96 chase, 5.8L inboard.
Inboard or Inboard/outboard?

i just bought it and discovered the plugs in the block were out and a frost plug missing.
That would be a casting core plug (aka welch plug)...... not a frost or freeze plug.

Put it all back together and it over heats. No leaks inside the engine compartment, oil is fine. I put die in the coolant to see if it was pumping out of the leg but it will not overheat sitting on the lawn with the dog ear on.
Is this engine fitted with a Closed Cooling System, or is it Raw Water Cooled?

The water existing the boat is warm. Opinion is the impellor shot? I took it out but the impelor looks good, but the boat has sat for two years.
Most any seawater pump impeller that has been left in the pump housing for two years has taken a "set" by now.
It should be replaced.
Also, during your winter lay-up, you should remove the impeller from the pump body.

any suggestions on what to look for? I have a pressure tester and will see if it is a head gasket but I think it is the heat transfer system.
You can perform a cylinder leak-down test. The leak-down test is used for determining where cylinder pressure is escaping.
If you are not loosing coolant, and if hydrocarbons are not entering the coolant (get yourself some test strips), this will not necessarily be your problem.


Appreciate any help. Chad
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What is your full engine model number?
Do you have one of the last AQ series stern drives (1996 was the last year), or do you have a Gimbal Suspension stern drive, or is this an Inboard?

Once you have the full engine model number, go here and look it up, and let us know.
https://www.marinepartseurope.com/en/volvo-penta-schematics-MarineGasolineEngines.aspx




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Thank you for the quick reply much appreciated. The boat is an inboard 5.8L with a volvo leg Serial 34112029256. It has a closed system with a fresh water half system I believe (lake boat here in the okanagan). The water from the lake goes thru the impeller and into a heat transfer tank of which the antifreeze also goes thru. I tried to explain what I did to eliminate as many possibilities as I could hence why I explained the hot water coming out and no internal leaks. What i did not understand that was if the coolant over heat it goes thru the overflow and into the heat transfer tank existing out the leg. This was major confusion.

I think you have answered my question as if the impeller has sat for 2 year it has probably set. I removed the water pump and pulled the impeller out, it looked good still pliable but I have ordered a new one nonetheless. I will post if this has corrected the over heating tomorrow. Once again very much appreciate the help.
Chad
 
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biggs7 said:
Thank you for the quick reply much appreciated. The boat is an inboard 5.8L with a volvo leg Serial 34112029256.
If this is a stern drive boat, it would be an I/B..... (aka inboard/outboard).
There will be an engine model number that will help identify the engine/drive package.
https://www.marinepartseurope.com/en/volvo-penta-schematics-MarineGasolineEngines.aspx

[FONT=&quot]The 5.8FIIHUBCE, 5.8FIPHUBCE, 5.8FIPHUECE, 5.8FLIHUB, 5.8FLIHUE, 5.8FLPHUB, 5.8FLPHUE, 5.8FSIPHUBCE, 5.8FSIPHUECE will be a Gimbal Suspension stern drive.
[/FONT]The [FONT=&quot]5.8FIPHURCE, 5.8FIPHUSCE, 5.8FLPHUR, 5.8FLPHUS, 5.8FSIPHURCE, 5.8FSIPHUSCE, will be an AQ series main suspension fork/pivot tube geometry stern drive.
[/FONT]

It has a closed system with a fresh water half system I believe (lake boat here in the okanagan).
That would be a Half Closed Cooling System..... meaning that the engine ONLY is in the Closed System Loop.
A Full Closed Cooling System will include the exhaust manifolds.
(FYI..... even while portions of the industry still uses the term, fresh water cooling is a misnomer in that there is nothing fresh about Ethylene Glycol. Technically, these are Closed Cooling Systems!)

The water from the lake goes thru the impeller and into a heat transfer tank of which the antifreeze also goes thru.
Yes, that would be your Closed Cooling System's "Heat Exchanger".
Seawater passes through the H/E's tube bundle, and E/G circulates around the H/E's tube bundle.


I tried to explain what I did to eliminate as many possibilities as I could hence why I explained the hot water coming out and no internal leaks. What i did not understand that was if the coolant over heat it goes thru the overflow and into the heat transfer tank existing out the leg. This was major confusion.
I am not following you on that one.

I think you have answered my question as if the impeller has sat for 2 year it has probably set.
When the impeller sits at rest within the pump housing, three or four vanes are left folded over against the impeller cam.
The impeller material can only be resilient for so long before is takes what we call a "set".
Once it takes a set, it is unlikely for it to become resilient again.

I removed the water pump and pulled the impeller out, it looked good still pliable but I have ordered a new one nonetheless. I will post if this has corrected the over heating tomorrow.
Keep in mind that with a Half Closed Cooling System, the exhaust is receiving seawater (river/lake/ocean water) and may become internally rust restricted.
You may want to remove the exhaust Elbows and examine the seawater transfer ports. These ports must be fully open and able to flow seawater.

TIP.... warm engine up prior to cracking the bolts loose. You can finish up after things cool back down.

Once again very much appreciate the help.
Chad
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