Volvo penta over heating

Hi new to the forum this will be a little long I have 1983 wells wellscraft with an aq125a the problem was it was over heating in a tank with muffs on so far I have changed the inline neck on the outdrive, cleaned and flushed all the lines changed the fresh water impeller,thermastat, cleaned both fresh water and holding tanks took off the exhaust manifold and found a hole in the donut connecting the outdrive to the manifold and a leaking gasket put a new donut and checked the flow on manifold and everything looked fine installed with new gaskets. Still over heated li pumped the oil and found water checked compression all sitting at 125psi. Changed the head gasket and checked head it was not warped changed the timing belt as well . Check compression sitting at 155psi in all 4 and did a leak dow test and no leaks. Started up motor to retorq head and the motor started to heat up to 180 I shut it down I also been checking it with a temperature gun in case gauge was faulty. Problem I found water in the oil again not antifreeze I'm stumped and have no idea what to do can the manifold be cracked inside and pushing water into the exhaust valves thanks

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fishgurru said:

Hi new to the forum this will be a little long I have 1983 wells wellscraft with an aq125a the problem was it was over heating in a tank with muffs on so far I have changed the inline neck on the out drive,
That would be the water neck fitting.

cleaned and flushed all the lines changed the fresh water impeller,
That would be the seawater pump impeller.

thermastat, cleaned both fresh water and holding tanks
Please explain "fresh water and holding tanks". Are you talking about the heat exchanger?


took off the exhaust manifold and found a hole in the donut connecting the out drive to the manifold
That would be the exhaust manifold rubber coupler. It joins the manifold to the down-tube.

and a leaking gasket put a new donut and checked the flow on manifold and everything looked fine installed with new gaskets. Still over heated li pumped the oil and found water checked compression all sitting at 125psi. Changed the head gasket and checked head it was not warped changed the timing belt as well . Check compression sitting at 155psi in all 4 and did a leak dow test and no leaks. Started up motor to retorq head and the motor started to heat up to 180 I shut it down I also been checking it with a temperature gun in case gauge was faulty. Problem I found water in the oil again not antifreeze I'm stumped and have no idea what to do can the manifold be cracked inside and pushing water into the exhaust valves thanks

When you did the cylinder-leak-down-test, did it indicate any issues?
You can also use hydrocarbon test strips to see if combustion gasses are entering the coolant.
As for the exhaust manifold, it is a likely candidate for water intrusion. If you pressure test it, use hot water.

As for cooling and/or over-heating......, the water neck fitting must be seated well on it's special beaded gasket. The bead must face down!
The pivot tube upper bushing must be good (no excessive play).
The lower pivot tube O-ring must be good.
The lower pivot tube needle bearing must also be good (no excessive play).
The S hose cannot have any air leaks within, or at either end.
The chrome water tube must be good.
The seawater pump suction hose must be good (no suction breach).

Click to expand...

Sorry was late at night and frustrated 1 I replaced the water neck fitting with a new one and gasket jlead the surface before I installed with the new gasket 2 Iinstalled a new sea water impellar and all the gaskets and o rings on the pipes and pump. 3 i took off the fresh water tank and cleaned the heat exchanger and cleaned the brass insert with muric acid also cleaned the tank for the antifreeze all orings and gaskets are new. 4 i found the manifold coupler had a ripe from the clamp so i took off and replaced with a new one and took off the exhaust manifold and found a defective gasket were water was being sucked in ran water through the manifold and it came out of the end and not the exhaust ports so installed with new gaskets and torque to 25lbs . Changed the oil 2 times then ran the motor in a tank with muffs climb to 180 and shut it down checked oil had water in it. Did a compression check and all 4 cylinders were 125 figured it might be a head gasket so I changed it and had a leak down test done told everything was fine and compression was 155 in all 4 cylinders. When installing the head was checked for any warping and the valves checked by a machine shop it was fine and while I was at it i replaced the timing belt Started the motor runs great but slowly climbed to 180 shut it off did oil change and found water again. All the houses and connections on the freshwater system was checked and all the hoses were replaced.Last time I ran it there was no water leaks and the raw water pump was pushing water . As for the pivot tube and needle I have know idea where that is thanks

What rpm are you running at while on muffs?
Personally, I don't like muffs.. several opportunities for problems
1) wrong muffs/improperly installed... you get too much air sucked in and engine overheats.
2) too high a water flow from hose.....water gets to places in engine it should not
3) too high an engine rpm ( should be not much above idle).... not enough cooling

My preferred way to run Volvo engines ( and other engines with engine mounted raw water pumps) "on the hard"
1) Flusher "T"method
a) plumb in a marine grade "T" , shut off (1/4 turn stainless/bronze) and hose bib valve before the raw water pump.
b)attach a short (3 to 4 ft) section of garden hose to the hose bib input
c) put other end of this hose into a 3 to 5 gal bucket
d)shut off the shut off valve and open the hose bib valve
e) let a garden hose to a source of fresh water free run into the bucket until the bucket is 3/4 full
f) start/runengine
***DO NOT LET water level drop to where the raw water pump sucks air!!!***
g)To use engine, shut engine off, shut off hose bib valve ,disconnect short hose, open shut off valve. Operate engine as usual

2)BIG F****G Bucket Method
a)Find a LARGE bucket or trough big enough for the stern drive to immerse almost up to the bottom of the cavitation plate. You should remove prop for safety reasons.
b)Put a free running hose into the bucket and make sure water level does not drop more than an inch or so below the bottom of the cav plate.
***Be aware of the fact that the engine will be recycling some of the hot used water ***

Method number one has several other advantages,especially if the engine has a heat exchanger.
1) can be used during season to flush engine if you run in sea water
2) Very easy winterizing (HEAT EXCHANGER EQUIPPED ENGINES ONLY!!!) Dump 2 to 3 gallons of antifreeze in bucket, start , run engine. shut off before it runs dry.

Always ran it at idle speed the tank is a 45gallon drum and we ran it with the hose attached and in the tank that was full of water the hose we set the flow at about half so a good flow was going throgh the heat exchanger at all times because the drum sits at a 45 angle next we ran it in the tank with the hose flowing. The motor was ran both ways it still got to high on the temp going to take the exhaust manifold off and do a pressure test to see if there is a crack inside

Talked to a friend whose dad was an old marine mechanic retired and explained everything was told how to set a pressure test lay the manifold on its side plug the exhaust and water output and fill the exhaust ports with water used a compressor at 8lbs and blow down the tube from the raw water tank up into the exhaust manifold and if I see bubbles I'ts not worth fixing have to get a new one it tells me I have cracks on the inside well did what I was told and it bubbled like crazy so every time the motor was on the intake it sucked up water into the motor guess I'm done for this season will look for a new one in the winter thanks

this is a video of the test on the manifold

I'll explain an alternative method that I've used on my AQ131A for that past 30 years with no adverse results. AQ131 has a raw water filter canister attached to the heat exchanger plumbed between the raw water pump and the exchanger. I remove the filter cap and internal mesh filter. Assemble an approx. 1 foot length of garden hose, 1/4 turn shut-off valve and attach this to a garden hose. I wrap the 1 foot hose length with an old T shirt, etc., and force it tightly into the filter canister. Turn on the garden hose and gradually open the shut-off valve once the engine has started. Pressure from the garden hose forces water through the exchanger and also down the copper pipe to the raw water pump, providing sufficient lubrication to protect the pump impeller. Water oozes out of the filter a bit, but otherwise, this rig keeps the engine temp right at 175. As the exhaust manifold heats, you simply open the shut-off valve a bit more to keep the manifold comfortably warm to the touch. I've never experienced any noticeable deterioration of the impeller. As always, YMMV...

fishgurru said:

this is a video of the test on the manifold

Click to expand...

Your test is not taking into account the small mixing chamber port that is just inside of the exhaust outlet area.
This small hole directs the "spent" seawater into the exhaust flow.
The way that you have the manifold capped off simply allows your test air to enter the main exhaust chamber.
This is why you see the air bubbles.


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fishgurru said:

Talked to a friend whose dad was an old marine mechanic retired and explained everything was told how to set a pressure test lay the manifold on its side plug the exhaust and water output and fill the exhaust ports with water used a compressor at 8lbs and blow down the tube from the raw water tank up into the exhaust manifold and if I see bubbles I'ts not worth fixing have to get a new one it tells me I have cracks on the inside well did what I was told and it bubbled like crazy so every time the motor was on the intake it sucked up water into the motor guess I'm done for this season will look for a new one in the winter thanks

Click to expand...

The retired marine mechanic is thinking of a manifold that is fitted with a removable Elbow.
In this case, you would block off the elbow face of the manifold and pressure test it.
With a 1 pc manifold (such as what you have), you would need to somehow close off the mixing chamber port during a test.

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fishgurru said:

1 I replaced the water neck fitting with a new one and gasket jlead the surface before I installed with the new gasket

2 Iinstalled a new sea water impellar and all the gaskets and o rings on the pipes and pump.

3 i took off the fresh water tank and cleaned the heat exchanger and cleaned the brass insert with muric acid also cleaned the tank for the antifreeze all orings and gaskets are new.

4 i found the manifold coupler had a ripe from the clamp so i took off and replaced with a new one and took off the exhaust manifold and found a defective gasket were water was being sucked in ran water through the manifold and it came out of the end and not the exhaust ports so installed with new gaskets and torque to 25lbs .
Changed the oil 2 times then ran the Engine in a tank with muffs climb to 180 and shut it down checked oil had water in it.
Did a compression check and all 4 cylinders were 125 figured it might be a head gasket so I changed it and had a leak down test done. told everything was fine and compression was 155 in all 4 cylinders.

When installing the head was checked for any warping and the valves checked by a machine shop it was fine and while I was at it i replaced the timing belt

Started the Engine runs great but slowly climbed to 180 shut it off did oil change and found water again.
All the houses and connections on the freshwater system was checked
What are you referring to as a freshwater system?
The Volvo Penta OHC engines are fitted with a Closed Cooling System.
Via the Heat Exchanger, the seawater removes engine heat from the Ethylene Glycol mixture.

and all the hoses were replaced. Last time I ran it there was no water leaks and the raw water pump was pushing water .

As for the pivot tube and needle I have know idea where that is
See image below.

Click to expand...

Sorry he never mention that so the exhaust manifold could be in good condition the fresh water system I was referring to was all the hoses and connections from the outdrive to the raw water pump the flow through the heat exchanger is strong when you loosen the cap off the heat exchanger it pours out fast.Where would I still be getting water in the oil from if not from the exhaust manifold 5 oil changes before the head gasket and I just changed the oil after the temp hit 180 and had water some water in it. How do you check the pivot tube without ripping the outboard drive apart mine is the 270 outboard drive thanks for the closest marine mechanic is 2hrs away and know one around here works on volvo motors

Question what is the ideal temp on an aq125a at idle I been shutting it down when the temp needle hit 190 f

....I just reread your posts... Are you using muffs AND a large barrel???

The only goof-proof way to find your problem will be to start at the point of seawater entry.
Learn the seawater path and follow it to the point of exit.
Inspect each area and each component.
Replace suspect parts.

When all components are in good working order, you can safely use the garden hose and water muffs.
When using the muffs, the boat will be on the trailer and the engine will not be loaded (not producing much heat).
Again...... when all components are in good working order, the garden hose will provide enough cooling water.

I worked on these for 24 years.
When all is OK, I never found one that would not work on the muffs.

Do you have pics of the output hole of the exhaust manifold? There are slots around the large hole that the water comes out that get welded shut with rust and a baffel across the center of the large hole. The center baffle rots away and the water coming out the slots gets pushed back into the #4 port on the head. #4 port is usually the port that goes bad on the head some pics of the head will help.

I'll start from the beginning of where the water intake is on the out drive all the hoses and gaskets have been replaced except the one connecting to the water neck and tube going into the transom it looked ok and had no splits. As for the head it was taken to a machine shop that does aluminum heads and was checked over by them and was found in great shape and not to do anything but reinstall the head with a new gasket they cleaned the head and made sure it was all within specs but I never thought about taking a pic . Should I change the temp sensor in case its faulty and I bought a heat temp gun to verifi the temp at idle . If there is some water in the motor that I could not pump out will it cause it to over heat last time I got almost 5 liters out thanks for your help

Here is a "long shot!"

When installed, the seawater pump impeller must sit "proud" of the pump body by approximately .010" .
In other words, when the correct seawater pump impeller is installed into the pump body, it will protrude from the pump body by .010" or so.
This ensures a good seal against both the inside thrust surface, and the thrust surface created by the cover.
Make sure that cover is sealing well against the body. (a new gasket would be recommended)

Also, the impeller's vanes (the rubber blades) must undergo "folding" by the pump's cam.
In other words, as the impeller is being rotated, the pump's "cam" should be folding 3 or 4 vanes over as each vanes pass over the cam.
This is what creates the pumping action.

Suggestion:

Using a dial indicator caliper, measure the pump body's cavity depth.
Now measure the impeller's depth.
The impeller dimension should exceed that of the pump body's depth by .010" or so.

Watch the vanes as each one passes over the cam.
Make sure that the cam is good, and is not worn out.


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When I replaced the raw water impellar i order the whole kit and replaced everything inside including the the connection rubber that is installed in the pully for the distributor all the bushings and the seals were replaced

Question i took the hose that connects the outboard drive to the motor on the in side behind the motor when I put the muffs on no water comes out of the pipe and I hear water thought the pivot pipe was plugged when I reverse the hose and connected it to the pipe water poured out of the out drive now I'm wondering if the motor was not getting enough water making it start to over heat thanks Rick for mentioning to start from the beginning is that normal or do I have to tear apart the outboard drive and replace the pivot tube and gaskets

I put everything back together and made sure everything was right out out drive in a tube that was high enough with no muffs and hose running in the tub water flowed through no problem motor went up to 220 f put a temp gun at the area of the temperature sensor block hit as high as 195 f and thermastat open and went down to 185 fluctuating between 185 and 195 the gauge on the panel stayed around 210 f is that to high for the motor when its idling in the tank

While you didn't answer my last question directly I reread your posts and...

MUFFS ARE USED WHEN A LARGE TANK IS NOT AVAILABLE, normally its muffs OR a large tank. A setup where the raw water pump draws the water the engine needs as it needs it is a better diagnostic. If your tank is large enough for the inlet grills on the drive to be well submerged, ditch the muffs and run makeup water into the tank as needed.

That's what I did when you replied about the muffs I figured that the muffs were doing more harm then good so I borrowed a big tank and the water was well above the screens also kept the hose running at all times the water circulation was alot better sorry i didnt answer you earlyer. I always run it at idle speed and never put it in gear and rev it up thanks

Just a fyi do not run in neutral for extended periods the oil slinger in on the prop shaft and you can damage the upper gearbox as oil is not going to the upper verticle shaft bearings.

fishgurru said:

When I replaced the raw water impellar i order the whole kit and replaced everything inside including the the connection rubber that is installed in the pully for the distributor all the bushings and the seals were replaced

Click to expand...

Please explain!
This is a 1983 AQ125A............... correct?

fishgurru said:

Question i took the hose that connects the outboard drive to the motor on the in side behind the motor when I put the muffs on. no water comes out of the pipe and I hear water thought the pivot pipe was plugged. when I reverse the hose and connected it to the pipe water poured out of the out drive now I'm wondering if the motor was not getting enough water making it start to over heat.
thanks Rick for mentioning to start from the beginning.
is that normal or do I have to tear apart the outboard drive and replace the pivot tube and gaskets?

Click to expand...

The only gaskets re; the pivot tube would be the special beaded gasket.
The beaded gasket sits between the water neck fitting and the top horizontal portion of the main suspension fork.
The "bead" faces downward and seals against the upper-most portion of the pivot tube.
Remove the transmission ONLY for this work.

There is also an upper bushing that must be in good shape. To replace this bushing, the drive must be taken apart.

There is an over-sized O-ring at the bottom of the pivot tube that seals the pivot tube against the lower gear unit housing. Lower unit must be removed for this replacement.

fishgurru said:

I put everything back together and made sure everything was right out out drive in a tub that was high enough with no muffs and hose running in the tub water flowed through. no problem. motor went up to 220 f put a temp gun at the area of the temperature sensor block hit as high as 195 f and thermastat open and went down to 185 fluctuating between 185 and 195 the gauge on the panel stayed around 210 f is that too high for the motor when its idling in the tank

Click to expand...

Yes..... 210 is too high!

fishgurru said:

That's what I did when you replied about the muffs I figured that the muffs were doing more harm then good
The water muffs are used quite often. As said earlier, if/when (key words "if/when") all is good, the muffs will not present a problem.

so I borrowed a big tank and the water was well above the screens also kept the hose running at all times the water circulation was alot better sorry i didnt answer you earlier. I always run it at idle speed and never put it in gear and rev it up

Click to expand...

We do not need to stay at idle speed while on the muffs. When you read that this should NOT be done, it is a disclaimer!
When we check the progressive ignition advance, we need to increase RPM to see what the ignition is doing.
We do this while on the garden hose and water muffs!
I have done this countless times.... no issues!

Also, with the propeller removed, any gear selection can be made.

I am not sure where you are getting this less-than-accurate info.

kimcrwbr1 said:

Just a fyi do not run in neutral for extended periods the oil slinger in on the prop shaft and you can damage the upper gearbox as oil is not going to the upper verticle shaft bearings.

Click to expand...

Kim is correct.
While the prop shaft is static, the slinger pump will be in-active, so there is no oil being pushed up the transmission.
(the slinger pump's duty is to push "cooler" oil up to the transmission for heat removal).

Also, keep in mind where the oil level "high-point" is (pull the dip stick and you will see).

When in Neutral there is no load. The oil level will be sufficient (while in Neutral) to splash lubricate the transmission bearings.
And again.... no load while in neutral!




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Could the circulation pump be finished and not circulating the anti freeze fast enough or just not working how to check if its working do i have to remove it to check or is there another way

Do you have a cabin heater? The hoses going to and from the cabin heater should be close to the same temp. Other than that yea the impeller may be toast.

It only takes a few minutes until my cabin heater starts blowing hot air.

No theres no cabin heater and with all the raw water system replaced and clean the only thing that was not changed was the circulation pump on the motor and wondering if it's not strong enough to pump the anti freeze through the system

Did you replace the thermostat?