Volvo Penta 2003 (non-turbo), Overheating?

[Capt Ben]

Hi all,
I have placed many miles on this engine but all of a sudden it has started to overheat when at max cruising rpm (3000rpm). She will not overheat at 2300rpm. Sea water flow output has always been a bit weak but present. I have the heat exchanger and aux hot water tank installed.
Any ideas what could be causing the overheating at higher rpm's?

The sea water pump has a drip from the pump itself. Boat is in the great lakes (freshwater). I have never purged /cleaned the sealed cooling water system. Is there a cleaner I should run through it and then flush out? If so, what is the flushing procedure? I run pure antifreeze.

Advice would be most appreciated.
Thanks in advance,
Ben

[Doug Brown]

You should NOT run 100% full strength anti-freeze - it really doesn't cool or transfer heat very well as it makes a barrier coating on the engine's and heat exchanger water passages.

Any of the automotive radiator flush solutions will work.

When you refill, the 50/50% pre-mixed anti-freeze will work just fine.

I would flush out the engine with fresh water, then use a cleaner. Before refilling with anti-freeze, I would run the engine under load at 3,000 rpm to insure the heating problem is gone - and then re-fill with new 50/50 solution.

And fix the water pump leak!

[leftbrainstuff]

Originally Posted by Doug Brown

You should NOT run 100% full strength anti-freeze - it really doesn't cool or transfer heat very well as it makes a barrier coating on the engine's and heat exchanger water passages.

Any of the automotive radiator flush solutions will work.

When you refill, the 50/50% pre-mixed anti-freeze will work just fine.

I would flush out the engine with fresh water, then use a cleaner. Before refilling with anti-freeze, I would run the engine under load at 3,000 rpm to insure the heating problem is gone - and then re-fill with new 50/50 solution.

And fix the water pump leak!

+1. Antifreeze works mixed with water not neat. Mix it as directed. Unless you are use a premix already.

Root cause temp issues by measuring inlet and outlet temps. Ideally you know the temps before you have a problem. If not no problem.

A hand held non contact infra red temp gun will cost just $30 these days. Note down the inlet and outlet temps throughout your closed loop and raw water systems. The fault will be obvious.

Sent from my SM-N900T using Cruisers Sailing Forum mobile app

[Neptune's Gear]

Temp check with gun is good as above.
Then start with the simple stuff. Pump impellor, thru hull not blocked, sea cock fully on etc. Then how hot is the heat exchanger - it should never be too hot to touch, if it is its restricted - has too little flow - so its fouled, the pump isn't working properly, or there is a blockage somewhere. Thermostat working? If the water at engine output is really hot, but heat exchanger is cool, then the circ pump is the place to start.


Mine is the turbo version, and in the tube between the thermostat housing and the exhaust riser there is a small plastic insert (inside copper tube, you can't see it). It has a small hole in it, and that can block and will cause overheating. I've been told it is not in some of the non turbo ones, but if all else seems ok, its worth looking. It is often overlooked by service guys...
Good luck!

[Paul L]

You might want to check the exhaust riser. They corrode out fairly quickly, blocking the interior passages.
On the starboard side of the engine down behind the starter is a petcock for draining the coolant. Even when you take it out you may not get flow. clean it out with a wire and then flush the coolant side with a radiator cleaner and then multiple fresh water flushes. Then use an anti-freeze that gets changed every 1-2 years.

[Valmika]

If you have never cleaned your coolant system it is time to do so. Sometimes its easier to just pull the heat exchanger and have it cleaned out. i do my own with muratic acid (available at any pool supply) While your at it you can change your hoses and clean up your engine a bit.

[Capt Ben]

Thank you for the suggestions!
Mark, what is the dilution and procedure with the muriatic acid? I assume it's pretty diluted, say 3% or so. Is there a way to do this while leaving the heat exchanger attached? Will it eat hoses, etc. that's all part of the cooling water system? If necessary, what's involved with the removal of the heat exchanger? Do I need replacement gaskets? Instead of the muriatic, if I just ran some auto radiator flush product in the system for a bit would that do the trick?

Originally Posted by Mark Killam

If you have never cleaned your coolant system it is time to do so. Sometimes its easier to just pull the heat exchanger and have it cleaned out. i do my own with muratic acid (available at any pool supply) While your at it you can change your hoses and clean up your engine a bit.

[Capt Ben]

Paul,
RE the draining petcock, I'll be at the boat again tomorrow and will investigate closer but I'm wondering if this is an actual valve where one can attach a hose for draining. It sounds like you are recommending removing the petcock and then poking and cleaning with a stiff piece of wire. Or do you recommend only removing if there's no flow? Is this petcock mounted on the exchanger or on the block?

Originally Posted by Paul L

You might want to check the exhaust riser. They corrode out fairly quickly, blocking the interior passages.
On the starboard side of the engine down behind the starter is a petcock for draining the coolant. Even when you take it out you may not get flow. clean it out with a wire and then flush the coolant side with a radiator cleaner and then multiple fresh water flushes. Then use an anti-freeze that gets changed every 1-2 years.

[Capt Ben]

Neptune,
Thank you for the suggestions. Is there anything special about the thermostat? Must it be a Volvo part or can it be purchased at any auto part store?
Attached is a spec page for the engine. As I have the heat exchanger, I assume that I have the 'fresh water' cooled engine. Is that correct? Looks like the new one would be opening at 165°F and be fully opened at 188°F. In the old days I would just take it out and place in a pot of water with a thermometer and measure its' operation. As it's probably 25 years old, I guess I should just replace it!

Originally Posted by Neptune's Gear

Temp check with gun is good as above.
Then start with the simple stuff. Pump impellor, thru hull not blocked, sea cock fully on etc. Then how hot is the heat exchanger - it should never be too hot to touch, if it is its restricted - has too little flow - so its fouled, the pump isn't working properly, or there is a blockage somewhere. Thermostat working? If the water at engine output is really hot, but heat exchanger is cool, then the circ pump is the place to start.


Mine is the turbo version, and in the tube between the thermostat housing and the exhaust riser there is a small plastic insert (inside copper tube, you can't see it). It has a small hole in it, and that can block and will cause overheating. I've been told it is not in some of the non turbo ones, but if all else seems ok, its worth looking. It is often overlooked by service guys...
Good luck!

[Valmika]

Originally Posted by Capt Ben

Thank you for the suggestions!
Mark, what is the dilution and procedure with the muriatic acid? I assume it's pretty diluted, say 3% or so. Is there a way to do this while leaving the heat exchanger attached? Will it eat hoses, etc. that's all part of the cooling water system? If necessary, what's involved with the removal of the heat exchanger? Do I need replacement gaskets? Instead of the muriatic, if I just ran some auto radiator flush product in the system for a bit would that do the trick?

I would not do it with the HE attached. I use full strength Muratic in a 5 gallon bucket. You only need to use a few cups of the acid. Do not fill the bucket Put on heavy rubber gloves and don't inhale the fumes. it will clean it out quickly. I opened both end caps to the HE and poured it through a couple of times. I have a Westerbeke 42 and was able to buy a complete hose kit and en caps for the HE for about $125. I am not sure if the radiator flush will work as well but it is something you could do for your engine block Before you do the heat exchanger while the cooling systems is intact. That alone may solve your issue. I just like doing mine off the engine because it gives me a chance to clean and paint parts that I normally cant get to.

[Paul L]

Originally Posted by Capt Ben

Paul,
RE the draining petcock, I'll be at the boat again tomorrow and will investigate closer but I'm wondering if this is an actual valve where one can attach a hose for draining. It sounds like you are recommending removing the petcock and then poking and cleaning with a stiff piece of wire. Or do you recommend only removing if there's no flow? Is this petcock mounted on the exchanger or on the block?

It is actually a petcock, but it often gets blocked up if the engine has not been flushed for long while and then needs to be removed to clean it out.

[Capt Ben]

Hi Paul,

Upon investigation, it looks like I just have a drain plug? Does it look that way to you as well?

According to this Volvo exploded drawing it looks like a drain. It would be nice to set up a petcock to facilitate a hose for drainage. Would you have any idea what size pipe thread that plug might be? Looked to be close to 3/8".
See attached photo and exploded diagram.

Thank you,
Ben

Originally Posted by Paul L

It is actually a petcock, but it often gets blocked up if the engine has not been flushed for long while and then needs to be removed to clean it out.

[Capt Ben]

Here's the photo and drawing...

[Capt Ben]

I have put a round of Prestone flush in and ran it for a couple of hours at around 1400rpm. I have opened the petcock drain and there is no flow. I've poked in there with a 14g piece of wire and only dislodged a slight bit of slimey black sludge. I guess I will now attempt to remove the entire petcock valve body and then pock around further to attempt to achieve drainage.
When the valve body is re-installed, should I use a thread locker? I assume that it will unscrew in a counter clockwise rotation.

Should I be flushing with the thermostat removed so as to ensure maximum flow?

I'm having difficulty figuring out how to verify that the circulator pump is working properly. I do have an IR thermometer.

Originally Posted by Paul L

On the starboard side of the engine down behind the starter is a petcock for draining the coolant. Even when you take it out you may not get flow. clean it out with a wire and then flush the coolant side with a radiator cleaner and then multiple fresh water flushes. Then use an anti-freeze that gets changed every 1-2 years.

[Doug Brown]

If you are getting the slimy black ooze out of the block with the piece of wire, you're in the right spot!

The entire drain assembly will come out with a deep socket - which I think is around 13mm /1/2". If you have never had it out, it will be very snug, so just put nice slow pressure on the ratchet handle to get it to free up for removal.

Once it is out, you will usually have a "plug" of the black goo that prevents water from coming out. You need to break this free and get it out of the way with your piece of wire or small screwdriver.

If you really want to blow all of the slime out of the water passage, stick a length of hose into the hole (so you can aim the water into the bilge) and start the engine and let it run for about 10-seconds. This should blow all the crud out and get the water draining freely out of the block.

Once that has happened, let it all drain, fill with fresh water, drain, put in the flush fluid, and eventually another fresh water before finally going with you 50/50 anti freeze.

Good luck!