617 cooling issues - PeachParts Mercedes-Benz Forum

polarisrmk · #1 06-21-2010, 11:10 PM

I am currently putting a 617.952 into a boat . I have the cooling system hooked up exactly as it would have been in a mb car with a marine heat exchanger in place of the radiator. Once the engine gets hot only steam comes through the small tube to the over flow. I have tried getting all the air out of the system and the min the engine warms up all I get is steam. When I open the radiator cap when engine is hot coolant comes spewing out. Once it stops spewing coolant it occasionally will pump a small amount of coolant fallowed by yet more steam... Help!

leathermang · #2 06-21-2010, 11:19 PM

Did you drive this engine when it was in a car ?
I think they have instruments which will test for exhaust gases in the coolant fluid... I would try that soon myself...\
Does it have a new thermostat in it ?

polarisrmk · #3 06-21-2010, 11:29 PM

Quote:

Originally Posted by leathermang

Did you drive this engine when it was in a car ?
I think they have instruments which will test for exhaust gases in the coolant fluid... I would try that soon myself...\
Does it have a new thermostat in it ?

Yes has a new thermostat.... What would exhast gases indicate? Blown head gasket? No this is a junk yard motor

leathermang · #4 06-22-2010, 08:40 AM

Checking the CO level in the coolant is pretty easy....
so , yes, that would indicate some breach between the systems.....
but it can also be a problem with the water pump, corrosion in the coolant jackets...
In the old days when a rebuild was done it was SOP to take everything off the block and dip the block in some nasty stuff.. which would clean out those deep recesses of the coolant chambers... particularly at the lower back where the coolant movement slows down and allows stuff to drop out and that adds up over the decades..
I know lots of our engines get partial or complete rebuilds without being ' vatted' as it was called... it is really hard to cool an engine after it gets past a certain amount of restriction and insulation which this build up can produce..
Also, there can be no leaks in the coolant system with respect to ambient air... because that takes the boiling point down to pot on the stove temperatures.. so your system has to be pressurized to at least one bar ( plus or minus 15 lbs) to keep even normal heat input from boiling it....
Are you sure the injection pump and timing are right on... and the valves set correctly ? Just have to go for the basics before getting fancy in looking for the problem..

polarisrmk · #5 06-22-2010, 09:45 AM

Quote:

Originally Posted by leathermang

Checking the CO level in the coolant is pretty easy....
so , yes, that would indicate some breach between the systems.....
but it can also be a problem with the water pump, corrosion in the coolant jackets...
In the old days when a rebuild was done it was SOP to take everything off the block and dip the block in some nasty stuff.. which would clean out those deep recesses of the coolant chambers... particularly at the lower back where the coolant movement slows down and allows stuff to drop out and that adds up over the decades..
I know lots of our engines get partial or complete rebuilds without being ' vatted' as it was called... it is really hard to cool an engine after it gets past a certain amount of restriction and insulation which this build up can produce..
Also, there can be no leaks in the coolant system with respect to ambient air... because that takes the boiling point down to pot on the stove temperatures.. so your system has to be pressurized to at least one bar ( plus or minus 15 lbs) to keep even normal heat input from boiling it....
Are you sure the injection pump and timing are right on... and the valves set correctly ? Just have to go for the basics before getting fancy in looking for the problem..

engine starts and runs beautifully. valves were just adjusted the same way i have always done and never had any problems.... how hot can the engine get in degrees F before i have a problem on my hands?

vstech · #6 06-22-2010, 10:18 AM

how hot? who cares? you have STEAM... that means it's boiling... OR it has exhaust gasses venting into it.
with the motor cold, no pressure on the system, pull the cap and start it up. does the coolant bubble? it shouldn't.

polarisrmk · #7 06-22-2010, 09:36 PM

Quote:

Originally Posted by vstech

how hot? who cares? you have STEAM... that means it's boiling... OR it has exhaust gasses venting into it.
with the motor cold, no pressure on the system, pull the cap and start it up. does the coolant bubble? it shouldn't.

no coolant bubbling but also very very very little to no flow back into the resivoir. if i put cap on pressure builds up but no flow... I am pretty sure i have all of the air bubbles out of the system now.

Junkman · #8 06-22-2010, 10:01 PM

Since it is a boat, do you have easy access to it? If so, I'd pull the thermostat, disconnect the top radiator hose, start the engine & watch the coolant. Test the thermostat while you have it out. If the water pump pumps & thermostat works, put it back together. You could use a infared thermometer to make sure that the radiator doesn't have hot spots. Next I'd be in favor of doing a leak down test. Harbor freight sells a cheap setup for the leak down. At least then you'd know what wasn't sealing on the engine. You have probably made an ass/u/me/tion and are over looking a simple part. Don't jump to exotic (at least severe) conclusions like head gasket.

MTUpower · #9 06-22-2010, 10:35 PM

Is the coolant overflow tank connected to the lowest part of the coolant path?

polarisrmk · #10 06-23-2010, 12:56 AM

Quote:

Originally Posted by MTUpower

Is the coolant overflow tank connected to the lowest part of the coolant path?

yes it is attached at the lowest part.... and the bottle is mounted at the highest part.... just for fun i pulled the water pump tonight and the brand new water pump i put in it had seperated! impeller was just laying in the block. went down to autozone and bought a new one ... now i seem to have flow but still dealing with a bit of a steam issue but i don't think that i have got all the air out of the system yet on this go round. engine ran for a good 20 min and never got above 210 F. my next question is .... how hot is too hot for these engines i hope i have not ruined anything.

leathermang · #11 06-23-2010, 08:28 AM

We can't answer that ' how hot is too hot' question.
These are tough engines... but any particular engine can have a weak spot...been tweaked in the past, etc...
I would just keep trying to find the specific problem causing this symptom... if it will still start it probably has not YET been hurt by the over heating... but fix the problem as soon as possible so as to not ' press your luck'.....

4x4_Welder · #12 06-23-2010, 11:26 AM

100c is considered pushing it in the car, that's 212f so i wouldn't want to get over that. 180-190 is a good spot to run, any cooler and you start having some premature wear issues.
How level is the engine sitting?

vstech · #13 06-23-2010, 11:38 AM

80C is generally accepted as the operating temp of these motors. tha'd be 175F...
anything between 175 and 212 should be fine.
200 is a nice max in my opinion.

JimSmith · #14 06-23-2010, 11:56 AM

The issue with trapped air is the spot with the trapped air will reach a temperature that has nothing to do with the value your temperature monitoring sensor reads. Big temperature differences over short distances generate stresses that are not part of the design operating conditions. So, get rid of the air.

In a car, it is pretty simple. Just drive the car, nose up, on a decent incline and fill it, run it with the radiator cap off, and when ever the coolant level drops, add more coolant. Eventually the system, with a few good pinches of the hoses, will burp itself clear of air. Then you close the system and take it for a drive. If the water temperature is at all unstable, you have air in there still. Small quantities will usually get cleared just by driving over normal terrain if the bulk of the air is already out.

In a boat you will need to improvise a bit as the shaft rake angle likely puts the engine at a tilt already. The idea is the same though. You want the path through the pump to be solid with coolant, under a bit of extra suction pressure. You might be able to do this by putting the little tank on the upper deck, outside the engine compartment and fill the system, then run the engine. If you can, safely, give the hoses a few quick and firm squeezes/releases to pulse the system and dislodge any air bubbles that may be trapped. Then see what you get.

How is the "seawater" circulated through the heat exchanger? Sometimes these things use the boat's forward movement to improve flow or just plain heat transfer and running at idle may not be getting the heat to the heat sink fast enough - Mother Nature's solution is to run the delta T of the heat source to the heat sink up until the system balances out.

Jim

polarisrmk · #15 06-23-2010, 08:42 PM

Quote:

Originally Posted by JimSmith

The issue with trapped air is the spot with the trapped air will reach a temperature that has nothing to do with the value your temperature monitoring sensor reads. Big temperature differences over short distances generate stresses that are not part of the design operating conditions. So, get rid of the air.

In a car, it is pretty simple. Just drive the car, nose up, on a decent incline and fill it, run it with the radiator cap off, and when ever the coolant level drops, add more coolant. Eventually the system, with a few good pinches of the hoses, will burp itself clear of air. Then you close the system and take it for a drive. If the water temperature is at all unstable, you have air in there still. Small quantities will usually get cleared just by driving over normal terrain if the bulk of the air is already out.

In a boat you will need to improvise a bit as the shaft rake angle likely puts the engine at a tilt already. The idea is the same though. You want the path through the pump to be solid with coolant, under a bit of extra suction pressure. You might be able to do this by putting the little tank on the upper deck, outside the engine compartment and fill the system, then run the engine. If you can, safely, give the hoses a few quick and firm squeezes/releases to pulse the system and dislodge any air bubbles that may be trapped. Then see what you get.

How is the "seawater" circulated through the heat exchanger? Sometimes these things use the boat's forward movement to improve flow or just plain heat transfer and running at idle may not be getting the heat to the heat sink fast enough - Mother Nature's solution is to run the delta T of the heat source to the heat sink up until the system balances out.

Jim

the engine is fairly level maybe slightly higher in the front end. the sea water is pumped in the heat exchanger by the drive and not currently hooked up. I am using a hose to flow water through the heat exchanger. I did have the hose on pretty low flow as i wanted the thermostat to open faster and keep open to burb the air so i am thinking that once i have normal flow through the exchanger operating temps will be lower. I am also thinking of putting a ball valve in my "heater core bypass hose" to allow more air to escape from the head passages.... or possibly putting an electric pump on this hose to help flow (sort of the same idea as the 123 cars have). I do also believe that i may have some air trapped in the upper radiator hose. I am going to look into this some more when i get some time.... In the mean time i seem to have coolant flow and a constant temperature. starting is very easy and engine sounds good though tough to say cause it is very loud with no intake or exhaust on it yet.