Boats cost and cost and cost!! Yesterday I found oil in the fresh water cooling system of Treks engine motor making it look quite black. Theres no water in the sump oil though.

Also although theres plenty of water coming through saltwater system its cold coming out stern exhaust indicating maybe heat exchanger is blocked somehow as well.

Its pity because motor starts instantly and runs great.

Unless Im jumping to conclusions I think I need the engine stripped down, source of oil leaking into fresh water loop fixed, then rebuilt.

Suggestions for someone competent and trustworthy in or near Sydney who could do that much appreciated!

Trek....give Sandy Wallace a call....Yachtech Diesel Services. 0404950112. He'll
work on your boat on your mooring. I got him to fix my Bukh last year. A nice lad
and a very good mechanic. One of our locals who used to own a sailing school, uses
him and that would have to be a top reccomendation.

Thanks Sam Ive called Sandy and left a message on his voicemail

I agree with samsturdy. Sandy looks after our 2003 andwe can highly recommend him.

see if you have a oil cooler on your eng if so thats all that you need to repair.oil presure is higher than water and will force in easy. you dont say what volvo you have so i can be sure

I would take an educated guess that the oil in F/water cooling system is coming from your oil cooler .... that should be f/water cooled and the only common place where they 2 are in close proximity of each other.

Get the cooler pressure tested first before you outlay for a full overhaul. Just might save yourself a bucket of dollars.

Thanks for advice guys. My version engine doesn't have an oil cooler but the turbo model does. I expected to find water in the sump oil but strangely none, and no other symptoms, compression is good, motor starts instantly and has plenty of power and runs like a swiss clock. My first thought was split in head gasket but the usual other symptoms arent there.

The gearbox oil is cooled by the freshwater loop though. That's a possible source that Sandy suggested. I didn't think of checking that last time I was on board. Doing some serious investigating next week.

Grich - its a Volvo Penta 2003

Well the plot thickens, Sandy the mechanic and I cant identify why the cooling water is black .....

Last time I was on boat a week ago I drained the engines fresh water cooling system and kept that bad (very black) water with the "oil" in it in a white bucket and refilled the engine with fresh water.

On arriving at boat this morning with Sandy the mechanic the water that was black is now clear and the black stuff has settled to the bottom of the bucket in a 1mm layer! So its not oil. Also where there were puddles of it under the engine the water dried up and left a dry black sooty substance.

Sandy says the impeller in the freshwater pump is metal so its not rubber from that. There are some black hoses carrying the fresh cooling water I'm wondering if they are deteriorating inside. Ideas welcome!

Sounds more like exhaust soot, so perhaps the heat exchanger. Do the hoses run to a hot water system as well?

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Trek said..
Well the plot thickens, Sandy the mechanic and I cant identify why the cooling water is black .....

Last time I was on boat a week ago I drained the engines fresh water cooling system and kept that bad (very black) water with the "oil" in it in a white bucket and refilled the engine with fresh water.

On arriving at boat this morning with Sandy the mechanic the water that was black is now clear and the black stuff has settled to the bottom of the bucket in a 1mm layer! So its not oil. Also where there were puddles of it under the engine the water dried up and left a dry black sooty substance.

Sandy says the impeller in the freshwater pump is metal so its not rubber from that. There are some black hoses carrying the fresh cooling water I'm wondering if they are deteriorating inside. Ideas welcome!

What about waving a magnet over it to see if it's ferrous.

Ruled out exhaust soot, heat ex and no hot water system. Googling "black in coolant" lots of people have experienced the same including in cars and asked advice but none of them that I can find say if they ever fixed it and what it was.
Im buying a big fuel filter tomorrow and make a cooling water polishing system at least it will be gone.
And Sam, I will keep a sample for lab testing!

if you can get the eng no it will tell me the model and i can research the problem,black water with out oil is combustion gases, on a volvo this can be from the head gasket, top liner o ring if it has wet liners or injector tube if it has them, there is a test kit you use to get from repco or snapon to confirm it.also you are describing the water as clear when it sits, the water should have inhibitors and glycol in it and will have a green color never clear .if it is clear it might be engine metals. you dont need a polish filter to fix just a good flush and correct water treatment after the problem is fixed pm me if you want to know more.

Hi Grich, thanks for your advice. I will go to boat and get the engine number and let you know.

I think the black in the water is very much like exhaust soot like EC31 but mechanic Sandy thought its not possible so I eliminated that theory. But probably it is.

How can exhaust material get into cooling water? Is it split gasket?

Normally if you have a split gasket, or pin hole in the metal jacket, you will also see air bubbles in the cooling system when the engine is running. I am not familiar with the Volvo, but perhaps replacing a section of hose with some suitable temperature clear hose to see if that is happening.

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Trek said..
Hi Grich, thanks for your advice. I will go to boat and get the engine number and let you know.

I think the black in the water is very much like exhaust soot like EC31 but mechanic Sandy thought its not possible so I eliminated that theory. But probably it is.

How can exhaust material get into cooling water? Is it split gasket?

if the eng is a wet liner eng volvo will have a top o ring seal,when it faiis this will allow gas to escape down the join,water will not travel back because of pressure.if its a dry liner eng it will be gas creep in the head gasket.volvo did not use injector tubes on all eng,s but is a place to check if it has them on your eng. you have not confirm if cooling liquid is water or coolant, very important cause some irons in eng will go black if incorrect fluid, ec31 is correct about pressure in eng but will only turn up when eng under load. trek i am a diesel fitter with a lot of volvo eng rebuild experience on larger eng and these were the most common issues on them

If the black material settled then it would suggest that it's hard particles in suspension. Trek if you
rub the stuff between thumb and finger, does it feel metallic or rubbery or shell ??.

OK Im off to the boat now. Grich, I will get number and let you know.

If it helps I read on a forum that Volvo Penta 2003 is a marinized Peugeot car engine. Thats why they were too fragile for boats and the reason Volvo had to bring out a Solas version. The Workshop manual for the motor is here:

avdhoeff.home.xs4all.nl/zeilen_bestanden/Volvo-Penta-Type_2001-2002-2003T_Workshop-Manual.pdf

Sam, the black stuff is like black soot and if you squeeze it between you fingers its soft and smudges. There could be fibres in it. No metallic feel.

Then it really sounds like you've got exhaust water leaking into your fresh cooling water. Good luck.

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samsturdy said..
If the black material settled then it would suggest that it's hard particles in suspension. Trek if you
rub the stuff between thumb and finger, does it feel metallic or rubbery or shell ??.

thanks for the Manuel if you go to page 9 you will see the injector tubes i mention,the block is mono block so it will not be a liner and the head gasket should be good,the injector tubes are replaceable with out striping the eng but you will need the special tools to replace them, this will need to be done by volvo or if your mechnic has them, its about a 3 hour job.the reason the tube fails is normally a leaking injector seat witch allows gas and soot to split the tube.or incorrect fitting of tube the tube is made of copper.if a injector is leaking it will have carbon in the tube. after repair a easy check is to run the eng under load and poor water around the injector and look for bypass some times,you have to loosen injector hold down clamps while it is running and tighten them to get them to seat down.as i said pm me your number.be careful a lot of people have never changed these tubes.ps i dont want the job just want it done right.also if you have salt water entering your fresh you will have corrosion around your radiator cap and alloy leaving white gunk every where

Heres the engine number and a picture of the cooling water containing the black stuff poured into a schooner glass. Those black particles are falling to the bottom like snow and after a while it all collects at the bottom. Its a lot clearer now since I replaced the cooling water 4 times now (much less black stuff per sample) hoping it would rinse out. But not so. Theres a screwdriver there for reference. We're going to take the head off and see what we find I think.

that is not the eng number that is a casting number.i wont need the eng number as you sent a link to the Manuel,do not pull the head off to have a look unless you have found something,there is no coolant at all in that water,i would suggest you pull the heat exchanger and have it clean the block flushed out and then volvo coolant put in.it also possible to be o ring or sealant debris ,soot will wipe on your hand and have to be washed of,if its soot please check the injector tubes first they are in direct contact with the coolant

no 1 run the engine at load and look for gas bypassing the pressure cap
no 2 also while running under load pour fresh water with a litile soap in it around the injector body and look for gas escaping.if you find any leaks the tubes are damaged
a lot of good volvo eng get rebuilt because no one checks the tube first
head gaskets dont normally fail unless it has been over heated
a sign for a over heated eng is darker or burnt paint around the head area

Thanks Grich and Sam. Two years ago I did dismantle the heat exchanger and clean it. The seawater out the back of boat is warm when engine is running so I think it is OK. Since I had the engine it didnt overheat and theres no darker or burnt paint.

Sandy thinks that the injector tubes may be swaged in on this model requiring a special Volvo tool to get them out and maybe its necessary to take the head off to get them out and/or cut them out. Whats your advice? What is pressure cap? I will go back to boat tomorrow and try the soap water and see what I can find.

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Trek said..
Thanks Grich and Sam. Two years ago I did dismantle the heat exchanger and clean it. The seawater out the back of boat is warm when engine is running so I think it is OK. Since I had the engine it didnt overheat and theres no darker or burnt paint.

Sandy thinks that the injector tubes may be swaged in on this model requiring a special Volvo tool to get them out and maybe its necessary to take the head off to get them out and/or cut them out. Whats your advice? What is pressure cap? I will go back to boat tomorrow and try the soap water and see what I can find.

pressure cap is the radiator cap.sandy is right the tubes are swagged in and require the tools to pull them out and re fit them. the injector will not fit back in until they have been reswaged with the correct tools the job is designed to be done with the head still on the engine. the tool numbers are on the Manuel page 9. do the test and confirm the leak first.if you give me sandys no i can ring him.Regaurding the cooler its the fresh water side that needs cleaning.2 years is along time on a cooler and hot water out the back is not a indication of how clean it is

Maybe a silly question, but are there any rubber hoses in the circuit?

Wow Trek....I'm glad you've got grich62 on your side. Well done.

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Yara said..
Maybe a silly question, but are there any rubber hoses in the circuit?

no such thing as a silly question,just silly answers. volvo tend to use pipes and orings this eng has 2 rubber hoses that run from the header tank to water pump and the bleed pipe from engine to the header tank and should be checked,thats why i would clean out the cooler and block check hoses and refill with correct coolant as the water is also rusty.

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grich62 said..

Yara said..
Maybe a silly question, but are there any rubber hoses in the circuit?

no such thing as a silly question,just silly answers. volvo tend to use pipes and orings this eng has 2 rubber hoses that run from the header tank to water pump and the bleed pipe from engine to the header tank and should be checked,thats why i would clean out the cooler and block check hoses and refill with correct coolant as the water is also rusty.

So maybe the black stuff is bits of rubber from inside the hoses.

Thanks for help Grich. Sandy and I will be at boat next week and will let you know how we go. I think we have to buy the Volvo tool first and then I will get back to you. And we WILL put proper coolant in when the problem is fixed.

@Yara - I suspected the black rubber hoses too and pulled one off. No problem with them. The black stuff isnt in the water when it enters the head and is when it exits. I tested that with a $15 filter from Whitworths inline with the different hoses.

The conclusion .... Grich you were right to be suspicious about the lack of coolant in the water, and your magnet idea Sam, I should have tried that, the black stuff is cast iron fragments.

Sandy went out to the boat today with a magnet and thats what he found. Motor is fine, just needs flushing and put in coolant! Recommendations for what kind of coolant would be welcome.

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Trek said..
The conclusion .... Grich you were right to be suspicious about the lack of coolant in the water, and your magnet idea Sam, I should have tried that, the black stuff is cast iron fragments.

Sandy went out to the boat today with a magnet and thats what he found. Motor is fine, just needs flushing and put in coolant! Recommendations for what kind of coolant would be welcome.




I think I would want to know where the iron fragments came from! Fresh water pump perhaps?
Cheers Bob.

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UncleBob said..

Trek said..
The conclusion .... Grich you were right to be suspicious about the lack of coolant in the water, and your magnet idea Sam, I should have tried that, the black stuff is cast iron fragments.

Sandy went out to the boat today with a magnet and thats what he found. Motor is fine, just needs flushing and put in coolant! Recommendations for what kind of coolant would be welcome.




I think I would want to know where the iron fragments came from! Fresh water pump perhaps?
Cheers Bob.

Agreed Bob.

I believe they have come from the walls of the cooling system in its entirety. ie. The cooling system consists of holes bored through a cast iron block and the walls of those holes have oxidized. Previously I put a filter in line with the water and each time I flushed the cooling system with fresh water less was captured by the filter.

After we've flushed the motor a few times and put the right additives in we'll see if it comes back. Grich if you are around what additives do you suggest?