Coolant leaking out of heat exhanger cap

[T2P]

Volvo Penta AQ131 A
1992 Glastron 1700

I am a newbie. I got the boat last October, 2011. Cleaned out and checked the engine including the cooling system. The salt water impeller and gaskets were replaced. Everything is working fine except that the coolant leaks out of the heat exchanger cap when the temperature hits 175F.

I checked the heat exchanger throat and found a tiny nick where the cap's bottom seal seats. Could this be the cause of the leak? I am thinking of grinding/polishing the seat flat or sticking in a flat rubber seal over it.

Any suggestions or ideas about the cause of the leak? The cap is brandnew.

I am looking forward to taking it out for the first time this spring.

Thanks.

T2P

 

[kmarine]

Re: Coolant leaking out of heat exhanger cap

Try removing the burr with 600 or 1000 grit sandpaper. Im not sure how large the defect is. otherwise you will have to replace the heat exchanger or take it into a shop for repair.

 

[T2P]

Re: Coolant leaking out of heat exhanger cap

Try removing the burr with 600 or 1000 grit sandpaper. Im not sure how large the defect is. otherwise you will have to replace the heat exchanger or take it into a shop for repair.

The nick looks likw a flat-head screw driver was lightly driven into the seat. it is about 1/16th" wide, 1/16t" deep.

 

[Mullin]

Re: Coolant leaking out of heat exhanger cap

I have an aq125 and there is no overflow tank for the heat exchanger. If also you don't have an overflow tank, then make sure you don't top off the coolant because it needs a place to expand to and the easiest thing to move is the spring loaded cap

Just draw out a cup or two with a turkey baster. Then test it again, bet it won't leak anymore.

 

[T2P]

Re: Coolant leaking out of heat exhanger cap

Thank you Kmarine and Mullin for taking the time to help with your suggestions.
I'll try Plan A (reduce the coolant level) and/or Plan B (deburr the nick) this weekend. I'll post the result next weekend.

For the meantime, I am still open to any ideas.

Thank you all.

T2P

 

[T2P]

Re: Coolant leaking out of heat exhanger cap

Thank you Kmarine and Mullin for taking the time to help with your suggestions.
I'll try Plan A (reduce the coolant level) and/or Plan B (deburr the nick) this weekend. I'll post the result next weekend.

For the meantime, I am still open to any ideas.

Thank you all.

T2P

I got to do Plan A and B today. The coolant stopped leaking out of the heat exhanger cap. Took out enough coolant to get the level about half an inch below the seat of the refill orifice.

I run the motor for about 5 minutes. Another issue came up this time. The temp reading went past 200F and had steam coming out of the cap. I know this calls for another thread but I'm posting this issue in the current topic , anyway.

I read in another posting about checking out the thermostat valve. What should I look out for? Should I do this or are there other possible causes I should check out first?

 

[T2P]

Re: Coolant leaking out of heat exhanger cap

I got to do Plan A and B today. The coolant stopped leaking out of the heat exhanger cap. Took out enough coolant to get the level about half an inch below the seat of the refill orifice.

I run the motor for about 5 minutes. Another issue came up this time. The temp reading went past 200F and had steam coming out of the cap. I know this calls for another thread but I'm posting this issue in the current topic , anyway.

I read in another posting about checking out the thermostat valve. What should I look out for? Should I do this or are there other possible causes I should check out first?

BTW, I was running the motor with the raw water intake (lower unit) submerged in a 30-gallon tank. I checked the raw water filter screen cannister and water is positively being pumped from the tank. Should this setup suffice for the tests or should I bring the boat to the lake? i am afraid there might not be enough water from the 30-gal tank or it is not as cold as lake or sea water.

 

[Mullin]

Re: Coolant leaking out of heat exhanger cap

The 30 gallon trash can should be ok, but I don't think you will be able to monitor the water discharging through the exhaust outlet to know you are actually getting a good flow. I haven't tried a bucket but I have tried two other ways; First is useing water ear muffs on the leg, you need to plug the hole on the very bottom to the leg with a rubber stopper or a cork or something. Second is to detatch the rubber connecting hose for the water pickup between the motor and the outdrive, just behind the back of the motor near the coil. Stick the garden hose into the rubber hose going to the motors pickup, just don't over pressurize the system, it helps to have a buddy to turn the water on and off. The lake is good too, but it sucks to be out there and overheat.

When you pulled the cap on the strainer, was the motor running and water started flowing out of the opening? It should. I don't think you would have been able to heat up the tank of water in 5 minutes to the point it wouldn't carry enough heat away from the motor, that's a lot of water. Heck it takes about 5 minutes for mine to warm up enough to open the t-stat.

You can test the thermostat. Pull it from the motor (thermostat housing attaches to the top right of the heat exchanger). Put it in a pot of water and a probe type cooking thermostat if you have it. Boil the water on the stove. The thermostat should be fully open before the water boils, at 180F. They are pretty cheap and available here on iboats. Use the 180F, this motor runs like crap any colder.

 

[T2P]

Re: Coolant leaking out of heat exhanger cap

When you pulled the cap on the strainer, was the motor running and water started flowing out of the opening? It should. I don't think you would have been able to heat up the tank of water in 5 minutes to the point it wouldn't carry enough heat away from the motor, that's a lot of water. Heck it takes about 5 minutes for mine to warm up enough to open the t-stat.

You can test the thermostat. Pull it from the motor (thermostat housing attaches to the top right of the heat exchanger). Put it in a pot of water and a probe type cooking thermostat if you have it. Boil the water on the stove. The thermostat should be fully open before the water boils, at 180F. They are pretty cheap and available here on iboats. Use the 180F, this motor runs like crap any colder.[/QUOTE]

There is a lot of water coming out of the strainer cup when I took out the lid with the motor running.
Yesterday, I opened up the thermostat housing. There was no T-stat. What was left was just the base and the rubber seal. The former owner took it out and never replaced it. I got a new t stat from West Marine today.

I have taker out the whole coooling system. what the heck. I might as well check out everything and learn something about my boat's systems.

First to come out was the heat exchanger and the strainer cup. There was a lot of gunk in the raw water plates. I dipped the heat exhanger housing and the raw water cooling element in an acid solution and flushed them out. Lots of brown , rusty stuff came out.

BTW, when running the motor, I think there is very little water coming out of the discharge outlet. I am not sure how little is little but it is not definetly not as much as was coming out of the strainer cup. I suspect the discharge outlet or the exhaust manifold channels may be clogged.

This afternoon, I'll be checking out the oil cooler and the exhaust manifold.

 

[T2P]

Re: Coolant leaking out of heat exhanger cap

I have put the heat exhanger assemble back together. Installed new seals and gaskets. Refinished the red paint and replaced all bolts and screws with stainless steel.

I took out the exhaust manifold this afternoon. It was not as difficult to take out as I expected it to be.
As i removed the copper pipe from under the manifold, two almond-size pebbles dropped out of it. The bad news: I found a hairline crack from the end of the exhaust manifold that run up to about four inches from the bottom. The rubber hose/connector kept the water from leaking out of it.

The water jacket/outlet holes where clogged about 75 percent. There is significant corrosion where the exhaust channel meets up w the raw water discharge outlets.

i will be shopping around for a new exhaust manifold. Any suggestions where to get a good deal?

 

[T2P]

Re: Coolant leaking out of heat exhanger cap

Update:

I did not find any oil cooler tube. The volvo manual said it should be under the exhaust manifold bhind the oil filter. Am i missing anything?

 

[Mullin]

Re: Coolant leaking out of heat exhanger cap

Sorry mine does not have the oil cooler. The copper pipe would go from the discharge of the heat exchanger (back of the strainer) to either the exhaust manifold directly (like mine) or to a oil cooler first, right below next to the oil filter.

Sucks to hear about the manifold. You might want to clear out the water jackets in the block while you are at it seeing how bad the manifold was.

Ebay has manifolds:

used: http://www.ebay.com/itm/Volvo-Penta...ear&vxp=mtr&hash=item2a1c4fcd80#ht_500wt_1413

new: http://www.ebay.com/itm/Marine-Exha...ar&vxp=mtr&hash=item35bb497171#ht_3669wt_1139

Not too expensive either.

 

[T2P]

Re: Coolant leaking out of heat exhanger cap

Sorry mine does not have the oil cooler. The copper pipe would go from the discharge of the heat exchanger (back of the strainer) to either the exhaust manifold directly (like mine) or to a oil cooler first, right below next to the oil filter.

Sucks to hear about the manifold. You might want to clear out the water jackets in the block while you are at it seeing how bad the manifold was.

Ebay has manifolds:

used: http://www.ebay.com/itm/Volvo-Penta...ear&vxp=mtr&hash=item2a1c4fcd80#ht_500wt_1413

new: http://www.ebay.com/itm/Marine-Exha...ar&vxp=mtr&hash=item35bb497171#ht_3669wt_1139

Not too expensive either.

Thank you for the links at ebay, PO2Cl Mullin. I made an offer for $75 for the used manifold and the gentleman accepted. It should be on its way by tomorrow.

Looking at the photograph of the ebay item, I realized that the part that extends from the inside of the exhaust ports to the end of the piece in my manifold has been corroded out of existence by about the length the rubber hose slips into the thing. No divider at all.

I don't mind doing more work on the engine. And thanks to the information you guys are giving, I am learning a lot and having fun too. This is my first boat and I must say the fears I have regarding its operation are turning into more confidence as I learn about it's systems.

I will give an update when the exhaust manifold arrives and get installed. or the meantime, I'll be doing some cleaning and cosmetic touch-up on the rest of the cooling system.

Have a nice weekend.

 

[Mullin]

Re: Coolant leaking out of heat exhanger cap

Wow, $75 is a great deal! Make sure you put the boot on the pipe or manifold before bolting up the manifold. When they are all in place, it is crazy difficult to get the boot on after the fact. I got it done but thought I was going to tear my new $80 boot in the process.

Make sure to check the water jacket on the block, if the manifold was that bad I bet it's all clogged up too.

Post a picture of your boat!

 

[T2P]

Re: Coolant leaking out of heat exhanger cap

Wow, $75 is a great deal! Make sure you put the boot on the pipe or manifold before bolting up the manifold. When they are all in place, it is crazy difficult to get the boot on after the fact. I got it done but thought I was going to tear my new $80 boot in the process.

Make sure to check the water jacket on the block, if the manifold was that bad I bet it's all clogged up too.

Post a picture of your boat!

Willco. Thanks.

 

[T2P]

Re: Coolant leaking out of heat exhanger cap

Wow, $75 is a great deal! Make sure you put the boot on the pipe or manifold before bolting up the manifold. When they are all in place, it is crazy difficult to get the boot on after the fact. I got it done but thought I was going to tear my new $80 boot in the process.

Make sure to check the water jacket on the block, if the manifold was that bad I bet it's all clogged up too.

Post a picture of your boat!

I finally completed all repairs to the cooling system. That $75 manifold I got from ebay had to be returned to the seller. It had an internal crack and could not be used. I ended up buying the other manifold, also from ebay. It is brand new.

I have now an almost brandnew cooling system.

Fired it up in the garage and the temp is rock steady at 195F.

I took it out finally to the water at Lake Hodges (Escondido, San Diego County) last weekend. There was a little problem powering it up to speed and the boat wouldn't go beyond 5mph without dying out. It looked like the spark advancer in the distributor is not responding or a bad carb. The carb has been cleaned and rebuilt earlier so I went for the easier fix--looking into the spark advancer or ignition timing advancer. There was no vacumn hose attached to the distributor. That was a puzzle. An advance system must be in place somewhere. I didn't want to waste any daylight looking for the advance and just sprayed a liberal quantity of wd40 silicon lubricant under the rotor and wiggled it a bit.

Fired up the engine again and wow! The engine came alive and can do 35 to 40mph at three quarters throttle. Spent two hours non-stop running around the lake. The engine temp held at 195F.

Thank you all who help me on this. Thank you PO2Cl Mullin for the heads up on the boot. Yes, it would have been difficult to get the boot on after everything's been in place.

The boat is ready for the summer.

A picture of my boat follows. It is a 1992 Glastron 1700, 17ft; volvo penta AQ131

 

[Maclin]

Re: Coolant leaking out of heat exhanger cap

As you noticed, boat engines will not have a vacuum advance mechanism, only the mechanical advance in the distributor, glad you found that problem. It may creep up on you again, look into a distributor rebuild or replace.

 

[Mullin]

Re: Coolant leaking out of heat exhanger cap

Good stuff T2P! Yeah, like Maclin said, it has a mechanical (centrifugal plates) mechanism under the rotor for advance. It might have had some deposits or rust holding is stuck in place. Good catch on the cracked manifold, that could have been a big waste.

35-40mph is pretty darn quick! Hey I know Lake Hodges...I'm nearby in Big Bear Lake. I always look at that part of the lake you can see from the I15 and think 'I need to go bass fishing there one day'.