Volvo Penta 2003 (non-turbo), Overheating?

[Dsanduril]

I wouldn't be overly concerned about a cool heat exchanger body if the coolant temp is good. The seawater pump on these engines is somewhat oversized (for lack of a better description). It is a positive displacement pump and has to provide full cooling water flow at idle RPM. Above idle it increases its output (linearly with RPM). Hence the whole bypass setup on the engine, you don't want to put excessive back-pressure on a PD pump, so the bypass system takes all the seawater that is in excess of that required for cooling.

In the freshwater cooled version the HE is essentially the bypass, and takes the full flow of seawater all the time. Since this flow is in excess of the amount actually required to cool the engine under most conditions (unless you have a very warm seawater inlet temperature) it can transfer all the heat out of the HE without increasing the seawater temperature a great deal.

[jimbunyard]

If you have air in the system, that would certainly lead to cooling problems. It must be bled out.


If you have the freshwater cooling system as shown in the attached drawing, then this information:

Originally Posted by Dsanduril

I wouldn't be overly concerned about a cool heat exchanger body if the coolant temp is good. The seawater pump on these engines is somewhat oversized (for lack of a better description). It is a positive displacement pump and has to provide full cooling water flow at idle RPM. Above idle it increases its output (linearly with RPM). Hence the whole bypass setup on the engine, you don't want to put excessive back-pressure on a PD pump, so the bypass system takes all the seawater that is in excess of that required for cooling.

In the freshwater cooled version the HE is essentially the bypass, and takes the full flow of seawater all the time. Since this flow is in excess of the amount actually required to cool the engine under most conditions (unless you have a very warm seawater inlet temperature) it can transfer all the heat out of the HE without increasing the seawater temperature a great deal.

is inaccurate at best.

In a properly operating system, the (fresh)water temperature at pipe number 7 in the drawing should be the same temperature as the engine, where it enters the heat exchanger. As it travels through the heat exchanger, is should be gradually cooled down until it exits the H/E into pipe number 8 at the opposite end, from which it is recirculated back through the engine, via tube number 13.

Tube number 12 is the bypass tube, through which freshwater flows (is recirculated, bypassing the H/E) until the engine warms enough to block the bypass orifice, thereby sending the now hot freshwater back for cooling through the outer jacket of the H/E, which is why the outer surface of the H/E should be more close to the engine temperature than not.

The flow of raw water is not regulated, except for by the speed of the engine, linearly as noted, or possibly by (unwanted) restrictions downstream of the r/w pump.

The raw water goes into the H/E through tube number 6, travels down one side of the H/E, back up the other side to exit into tube number 10, thence to the exhaust elbow and into the exhaust stream.

As far as I can tell, the circulation pump is a fixed impeller centrifugal pump, not positive displacement, the raw water pump is a flexible impeller pump which is positive displacement.

And finally, the provisions for hot water shown in the diagram seem to be laid out to self bleed. Are yours set up so the water goes to the heater from the fitting at position 23 and returns via the fitting at position 21?

[Dsanduril]

I think the information is accurate, maybe I did a poor job of explaining it

I was trying to make the comparison between the raw water cooled engine and the HE cooled. They both use the same seawater/raw water pump (a PD pump). The HE cooled engine adds a second pump for coolant circulation. On the raw water cooled engine there is a bypass on the top of the engine connected to the thermostat housing (and that bypass is discussed in the thread above). In the raw water cooled engine that bypass serves to keep the PD flow steady.

In the HE engine the raw water pump (PD) pumps directly through the HE, at full volume, all the time. In that sense, the HE becomes the flow relief for the PD raw water pump so that flow is maintained, a job that the bypass tube has in the raw water cooled version.

Except in high inlet temp raw water locations the raw water pump generally provides more than enough water flow for cooling and the bypass generally has some flow (exact amount depends on inlet water temperature and engine load). Thus when the same pump is used to pass the cooling water through the HE it has more than enough flow to carry away all the generated heat. And thus I would not be surprised the HE feeling relatively cool, and would put much more weight on the coolant temp than on the HE shell temp.

[Capt Ben]

Thank you very much to all that have contributed their advice and experience!

I'm beginning to believe that the initial overheating of this engine has caused damage such that compression may be compromised. If this is the case, could that cause present day overheating when more fuel is burned (hotter) to try and achieve similar performance?

I have successfully cleaned out the heat exchanger by doing an acid bath and cleaning all of the passages. I estimate about 1/3 of the passages were partially blocked and a good amount of calcified debris was near one end of the ports. The engine has been flushed a few times, completely drained and re-filled with a 50/50 mix. After extensive bleeding of my heater hose lines, I again have hot water for my sinks etc., yet she still overheats when above 2400rpm. I have bought the circulator pump rebuild kit and will next open that up and see if any ports are blocked or if theres somehow damage to the impeller. I have a feeling that the pump is okay because there would not be hot water circulating through my hot water heater. Is that correct? Even when not overheated, the engine feels weak, less power. Any guesses on what, if any, damage may have been done? Valves, rings? I have an old 1970 vintage compression tester that I'm thinking I will attempt to use on this engine as the last troubleshooting procedure after I've gone through the circulator pump which seems to be the last possible option...

BTW, when attempting to disassemble/remove the circulator pump with a 5mm hex T wrench, one bolt has broken. I expect the remaining two to break as well. As the pump is made of aluminum and the bolts are steel, I imagine that these bolts are completely seized. I've already purchased an extractor and a 6x1mm tap just in case. As the broken bolt broke relatively near the head, I estimate that once the pump is removed and split in half, that there will be about 1/4" of remaining bolt sticking out. I'm expecting to use heat and a solvent and vice-grips to remove the remaining broken bolt. (see attached photo of pump). Any great advice on this disassembly nightmare. I did use a small butane torch to attempt to heat up the closed body but the bolt still broke. Thanks to McMaster Carr I know own 50 of these bolts.

[deblen]

Did you find the engine block drain cock? It is hidden under the starter near the bell housing. The drain plug in the rear of HX will not completely drain the block as it is at a higher level.
Pic 3 from pg 5 of Svc Manual shws the cast boss at rear stbd side of block where drain cock fits.
http://www.bluemoment.com/manuals/vo...m=100,-225,694

Cheers/ Len

[Capt Ben]

Hi Len,

Yes, the block drain petcock has been removed and cleaned of any sludge, and now runs freely.
I do believe the block is flushed out pretty well.

[deblen]

Volvo Penta, Mercruiser and more - Marine Parts Express - engines, outdrives, propellers

I've had good luck getting VP parts here,Plus they have exploded view of eng. online.

At 2100 hrs,my 2003 was getting hard to start. I bought a VP decarbonizing gasket kit,pulled head,had valves ground & reass'd. Gained 150 RPM,starts well,more pwr oa.
Use new pipe seals,clean pipe sockets with wire bat term. brush or similar & use Vaseline-no leaks for 2 yrs now.

[Capt Ben]

Len,

Did you do this repair yourself?
When the valves were ground did the injector seats have to be removed and replaced?

So, you didn't get to the rings, just the head?

RE the De-Carbonizing Kit, #876310 $172.11 (Gasket kit)
This might be the right one for my 2003 (non-turbo). I've found this Volvo site a decent resource for parts on-line.

[deblen]

Originally Posted by Capt Ben

Len,

Did you do this repair yourself?
When the valves were ground did the injector seats have to be removed and replaced?

So, you didn't get to the rings, just the head?

RE the De-Carbonizing Kit, #876310 $172.11 (Gasket kit)
This might be the right one for my 2003 (non-turbo). I've found this Volvo site a decent resource for parts on-line.

I removed & re-installed the head myself.
I had a local eng. shop remove valves & old seals,grind valves & seats & reinstall valves with new seals. I did not have to have valve seats replaced.
I could not get my injectors out of the head-did not want to force & ruin existing copper sleeves. This was not a problem-I had no leaks & injectors were & are working fine. The eng shop gently cleaned the bit of carbon on/around tips.They were in great shape anyway.My 1984 model has a different "clamp" bolt setup that holds inj. in head & it's difficult to get a grip on the inj. to pull it.
The decarb gasket kit 876310 is for Turbo 2003T. The correct p/n for non turbo 2003 is 876309. You have to look carefully at top of exploded view pages to make sure you are on correct page(Sida in Swede) for your eng.I bought the paper parts manuals in 2006 when I got the boat & that helped me to find correct pages.The online ones are correct also but very easy to pick wrong page I find.


I did not go deeper into eng.-no need to- No ridge at top of cyls & crosshatch/hone marks still visible on cyl walls.

You will need a torque wrench & valve feeler gauge to re-install.If you have never torqued a head/adj. valves before,get help or Google it.Not rocket science but there is a proceedure & some no-no's.

Cheers/ Len

[Paul L]

As Len says the injector sleeves do not need to be removed to take the head off and work on the valves. If you are going this far it seems like testing the injectors would be something that should be done at this time. To do a compression test you will have to pull the injectors anyway. We ended up using an old injector and modified it to fit the compression tester. If you pull the injectors and the sleeves are eroded or leak, then you will probably have to go down the road of replacing and re-installing the injector sleeves. Not as straightforward a job as it should be.

A bit of unsolicited advise: Be cautious that you don't get into death by 1,000 paper cuts on the engine. Every time you drop $1500 you are 1/5 the way of a new Yanmar replacement engine.

[DeepFrz]

Capt. Ben, did you remove and clean the injection elbow? That is another source of overheating and loss of power.

[Capt Ben]

Still having overheating issues....
Has anyone suggestions for how to best flush engine coolant in block? I've done the prestone flush twice and am back to this as a possible solution.

-
Great seawater output now that I've cleaned the heat riser elbow.

-Acid bath cleaned heat exchanger. She's clean now.

-Thermostat checked.

-Circulator coolant pump opened up and it looks perfect.

-Hot water system works (sink and shower), coolant moves through hot water tank.

NOTE: If engine is revved over 2200rpm suddenly temp of tstat housing starts rising from 180 to 200+. Temp goes down when throttle is reduced.

BTW, should coolant nearly continually be entering the reservoir from tstat small hose? Might this occur if coolant doesn't move through block freely? I'll try blowing through system again.

Need to find the magic bullet that solves this issue asap. Thanks to all the great suggestions previously received.


Sent from my iPhone using Cruisers Sailing Forum

[Paul L]

As DeepFrz mentioned, have you dealt with the exhaust elblow yet?

[Capt Ben]

Paul,

Yes.

"Great seawater output now that I've cleaned the heat riser elbow "

Thanks though.



Sent from my iPhone using Cruisers Sailing Forum

[deblen]

Originally Posted by Capt Ben

Still having overheating issues....
Has anyone suggestions for how to best flush engine coolant in block? I've done the prestone flush twice and am back to this as a possible solution.

-
Great seawater output now that I've cleaned the heat riser elbow.

-Acid bath cleaned heat exchanger. She's clean now.

-Thermostat checked.

-Circulator coolant pump opened up and it looks perfect.

-Hot water system works (sink and shower), coolant moves through hot water tank.

NOTE: If engine is revved over 2200rpm suddenly temp of tstat housing starts rising from 180 to 200+. Temp goes down when throttle is reduced.

BTW, should coolant nearly continually be entering the reservoir from tstat small hose? Might this occur if coolant doesn't move through block freely? I'll try blowing through system again.

Need to find the magic bullet that solves this issue asap. Thanks to all the great suggestions previously received.


Sent from my iPhone using Cruisers Sailing Forum

Coolant does not move continuously from T-stat housing thru small 1/4" hose to plastic reservoir on my 2003.In fact,I have never noticed it moving thru the small hose at all,but I assume it occasionally does when coolant is extra hot & needs a place to "expand" to.Not sure how this part-the 1/4" hose-works.
Hope someone can explain it.
/ Len