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Volvo Penta (AQ125B) leaking coolant

 
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'85 Invader



Joined: 27 Jul 2007
Posts: 7

PostPosted: Fri Jul 27, 2007 6:44 pm    Post subject: Volvo Penta (AQ125B) leaking coolant Reply with quote

Looking for help finding/fixing a leak I have.
Few weeks ago the impeller went and the boat overheated.

When replacing the impeller noticed a leak at the top of the circulation pump (CP).

I bought a Serloc Manual (read it too), replaced the CP seal (one to the block and rubber one to the cylinder head). Replaced all seals/gaskets from the inlet pipes to the raw water pump, removed heat exchanger (HE), cleaned and replaced all seals, spacers and gaskets from the inlet to outlets. Did strip the fixed nut out of the elbow connector on the strainer housing (cost $150 new housing...ouch), while I was at it replaced all seals spacers and gaskets from the strainer housing to the HE.

With the HE off I replaced the thermostat and seals...interesting no one even Volvo has a part # showing a gasket between the HE and thermostat housing, (it leaked for a minute when testing, then stopped).

Front now appears to be tight, now I have coolant dripping at back rear of engine by oil pan (don't remember seeing that before), can's see where it's coming from..HELP!

Also, no water in oil.
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boatScotty
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Joined: 07 Nov 2006
Posts: 229
Location: Pacific Northwest

PostPosted: Mon Jul 30, 2007 10:33 am    Post subject: Volvo Penta (AQ125B) leaking coolant Reply with quote

There is no easy solution to this one.

I would suspect that you have a leak from one of the coolant pipes/lines to the exhaust manifold. Check everything on the back end religiously.

I like to use the 'wipe everything down with a paper towel' method.

Wipe the back of the engine and all other areas with clean paper towel.

I then take pieces of paper towel (I like the Scotts small sectional towels) but you can use TP or tissue; to place against/wrap every pipe/hose joint. I fire it up, let it run a minute and check everything (while cold).

No leaks cold, then I go onto the hot test. Fire her up and see if the leak is weeping when hot only. I put paper towel in places I cannot see, but may suspect a leak.

You will find it - and it is likely a hose/pipe connection.

Now you did make it clear - it is coolant that you see dripping, right, not water?
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'85 Invader



Joined: 27 Jul 2007
Posts: 7

PostPosted: Mon Jul 30, 2007 10:51 pm    Post subject: Reply with quote

Thank you,

I washed down the engine a few days ago, let everything dry then fired it up for a few minutes.

The leak did appear between the head and block, no coolant in the oil though, it was running down the block and dripping from the bottom.

Not the answer I was hoping for as now I have to pull the head and take it to a machine shop to see if it is warped. Did get gaskets (head intake and exhaust) for a Volvo 240 car as I was told they were the same engine and are considerably cheaper at Auto Zone. Thanks for the reply.
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boatScotty
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Location: Pacific Northwest

PostPosted: Tue Jul 31, 2007 7:31 am    Post subject: Volvo Penta (AQ125B) leaking coolant Reply with quote

Did they sell you composite gaskets then? or metal?

I would be putting in composite to seal and perform better

"Did get gaskets (head intake and exhaust) for a Volvo 240 car as I was told they were the same engine and are considerably cheaper at Auto Zone."
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'85 Invader



Joined: 27 Jul 2007
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PostPosted: Mon Aug 06, 2007 4:50 pm    Post subject: Reply with quote

The gaskets were composite for a 2.3L Volvo, so I think I am OK. Took the head to the machine shop, they are dong a pressure test as well as checking for warping (I used a straight edge and found an extremely slight warp at the center intake side the same location of the leak was .004, seloc said could only be .003, the rest seemed OK).

Question A final Q...is the Volvo Oil any different from Castrol? Have used Castrol in my cars forever and always had good luck. The valve cover says use 30 wt. the seloc manual 10w30 and a local boat mechanic (the one who suggested the machine shop) said he uses 20w40 mercruiser? It does get over 100 here in Central Cal for weeks on end and the engine is older so maybe the 20w40 wt oil would be better, but don't want to damage anything.

Anyhow...thanks to everyone for their advice, should be back in the water soon if all pans out
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MikeW
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Joined: 01 May 2006
Posts: 680

PostPosted: Tue Aug 07, 2007 3:21 pm    Post subject: Oil Type Reply with quote

Hello Invader, Castrol 20-40 is an excellent choice. Oil is the same in both Automotive and Marine Gasoline Powered Engines
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'85 Invader



Joined: 27 Jul 2007
Posts: 7

PostPosted: Wed Aug 08, 2007 1:31 am    Post subject: Reply with quote

Thank's Mike, will go with Castrol.

Machine shop called and verified the head out by .004 (said new gasket would probably have sealed it, but had him mill it since he had it). Rest tested very good, so now that it is done, time to put the pieces back together and get back on the water.
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MikeW
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PostPosted: Wed Aug 08, 2007 7:52 am    Post subject: Volvo 125 Reply with quote

Hello '85 Invader, good luck with your project! If you need anything else let me know.
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'85 Invader



Joined: 27 Jul 2007
Posts: 7

PostPosted: Mon Aug 13, 2007 9:42 pm    Post subject: Reply with quote

Got everything together, and no leaks.

NEW PROBLEM
Took to lake runs close to 200, not sure what is causing heat as I can idle up to 2k without any issues, but at 3 to 4k coolant boils out of HE Cap temp really doesn't go up on gauge though. Slowing down to 2k or below it stops. Have new thermostat everything else was clean. Sea water side works great as I can touch the exhaust manifold anytime and it is slightly warm but never scalding hot like it was before I pulled the head.

This is quite frustrating as I have replaced every gasket and seal from the head up through the heat exchanger and finally no leaks but not sure if it is just the cap or something more.

Any suggestions would be greatly appreciated as I really want to get back to the lake before summer ends.
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boatScotty
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Joined: 07 Nov 2006
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Location: Pacific Northwest

PostPosted: Tue Aug 14, 2007 10:49 am    Post subject: Volvo Penta (AQ125B) running hot Reply with quote

Invader,

Well, being the mechanical detective I am, I will ask a few questions. I will go with the gauge being accurate at 200 degrees. Your engine should be running at less than 200.

When you state that the coolant is ‘boiling out’ do you mean that it is so hot (say, above 220) to pop the cap? The gauge reads cooler, do you have a digital thermometer (available at Radio Shack) to point and read the temp? It could be a weak pressure cap. A point and shoot thermometer (as well as a mechanics stethoscope) has saved me many an hour in diagnosis of engines, transmissions and cooling systems.

My first reaction (IF it is overheating for real) is restriction – which I would check at the thermostat OR water pump impeller is giving you problems. You can check the opening of the thermostat in a pot on the stove and you can visually inspect the impeller.
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'85 Invader



Joined: 27 Jul 2007
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PostPosted: Tue Aug 14, 2007 12:41 pm    Post subject: Reply with quote

Thanks Scott

The gauge is hard to read as it shows 180 then three lines then 240 (simple math would summize the lines to represent 195, 210 and 225), When I tested it on the lake the readings were between the first and second line after the 180 mark...first line idle, just below the second line under load, never going above that. Hate this Volvo gauge as 90% of it will never be used as the reading is below the 180 mark, and the 10% actual running area to the right of the 180 mark is all within a quarter inch or so, no green yellow or red area on this gauge.

Will go to Radio Shack and get the digital thermometer to see if the temp is actually correct. By boil over I do mean that it is coming out around the cap (bubbling out when the cap is on), I plan to replace it as it might be a weak pressure cap as you stated, (another $20 in a long list of $10 to $60 add on parts I have replaced).

The impeller is new, checked it again when putting the HE back on (even disconnected the out side for a few seconds while running and had water spray out). This also would support the exhaust manifold being only warm to the touch when the coolant is boiling out at the cap, as it is cooled by the seawater cooling system which is supplied by the impeller.

Circulation pump appeared to turn smoothly when replacing the gaskets and is not slipping on the belt (this is a $900 part so was concerned early on). Will pull the new thermostat and check it in boiling water. As everything else is new (machine shop said the pressure test was good when they milled the head) so hitting a wall if the cap isn't the cause.

If you can think of anything I haven't would appreciate it....
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boatScotty
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PostPosted: Tue Aug 14, 2007 1:42 pm    Post subject: Volvo Penta (AQ125B) running hot Reply with quote

Invader,

About the cap - sometimes it is a weak cap and sometimes it is a bad gasket/seal. Clean up the gasket seal areas and put on a coat of vasoline to help it seal and then see if it bubbles again.

If I think of anything else, I post it. Good luck!
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'85 Invader



Joined: 27 Jul 2007
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PostPosted: Sun Aug 19, 2007 10:05 am    Post subject: Reply with quote

Got the new cap, went to the lake and it does sit stable under load and at idle at just under 200, (if I listen closely by the cap I can hear a light hissing after running at 3k+ for a few minutes, but no boiling over). Tested to old thermostat and it fully opened at 180, thinking about putting it back in as 180 leaves a little more flex room if a problem was to occur anytime in the future. Looked online for new a lower thermo and found nothing for the AQ125b engine, but found a 180 for a car A23 engine ('85 Volvo 244DL car, shows as a 2.4L [Auto Zone: Beck Arnley 143-0705 for $18.99 which is half what I paid for the marine 195 degree version]).
Think that will make a difference?
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MikeW
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Joined: 01 May 2006
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PostPosted: Mon Aug 20, 2007 4:23 pm    Post subject: 125 B running hot Reply with quote

Hello '85 Invader, sounds like you have fixed the problem. By the way 180 degrees is the correct opening temp. Are you still having any problems with water boiling out? If so make sure the heat exchanger is not plugged or dirty.
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maytermostats



Joined: 19 May 2009
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PostPosted: Tue May 19, 2009 9:46 am    Post subject: Reply with quote

You can check the opening of the thermostat in a pot on the stove... you can see the how is it...




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