Engine Overheating - Volvo MD2030

[zams 1006]

Hi everyone,

Been following the forums for a while but first time poster!

My Volvo MD2030 overheated today and I was wondering if anyone could provide some insight into the right course of action.

1. Left Mooring, began motoring. Easy to start with then to crusing RPM. Noticed a change in pitch of the engine and saw the water temperature rise to 190 Degrees+. Saw white steam/smoke (pretty sure it's steam) come out of the exhaust. Turned engine off and sailed back to mooring.

2. I've tried to trace the problem back. Sea water intake is clear, raw water strainer is clear. Took out the raw water pump. Impeller and pump seems fine (Installed new in Nov 2020). Drained coolant and dismantled heat exchanger, no blockages there either.

I suspect the issue must have been with the coolant circulation pump? Do these things fail often? I've never had engine issues before so this is quite new to me. If anyone has any advice or tips that would be great!

I've also got some photos attached for reference.

Thanks in advance!

[Wotname]

Welcome aboard zams 1006.

Was there any blockage where the raw water enters the exhaust system.

Did you have the usual (ie good) flow of raw water exiting the exhaust - if not, your problem is somewhere in the raw water circuit. I understand you have checked most of the raw water system but unless you have good flow exiting the exhaust, there is a problem somewhere in the circuit.

Yes, coolant pumps do fail but not very often, most go for decades without issues.

Check the thermostat for correct operation.

[simonluke]

I had the same problem with the MD 2020
I removed the heat exchanger to check the thermostat.
I replaced it as this is a lot of effort for what should be a simple swap out.
Having gone so far and without pressure testing equipment I decided to replace the cylinder head gasket.
To this day I don't think that was the problem.
My take on this is that the offending parts are the rubber end caps on the heat exchanger,they degrade over time and don't form the seal on the stack.
I was told you would have to be very unlucky for the fresh water pump to fail and you would probably see leaking.
If you have a calorifier is this heating up ok ?
Also if you fit new end caps make sure the stack has an equal overhang out of the exchanger and tighten up the jubilee clips with great care
Hope this helps

[zams 1006]

There was okay flow out the exhaust. I have a feeling it had been better in the past. I'll take apart the exhaust elbow tomorrow and check the hoses there for any issues. Surely that's more likely rather than a cooling pump.

[simonluke]

To the eye the flow through the exhaust might be ok but I eventually found out that the heat exchanger was not dissipating the heat sufficiently.
Check to see if you have salt traces in the coolant

[jimbunyard]

These are known for restrictions building up in the raw water side of the exhaust elbow, especially if you have the high rise version.

They may seem to pass enough water, when in fact they do not. From memory, flow should be on the order of 2-4 gal/min.

The advice given previously about the boots is sound; make sure the sealing areas are clean to bare metal, the small bleed hole in the HE bundle is at the top when you reinstall it, that the bundle is centered in the HE housing, that the boot clamps are tight and that the boots don't have any attached scale on their sealing surfaces. Depending on the severity of the interchange between fresh and salt water, leaking boots may or may not cause overheating, but having saltwater in the freshwater side kinda defeats the whole HE purpose...

Could also be simply a bad t'stat, which ain't so simple as you have to remove the HE housing to get at at it.

Fresh water pump would be my last suspect.

Is it summer where you're at?

[jimbunyard]

Originally Posted by jimbunyard

...Fresh water pump would be my last suspect...

Unless there's obvious play in the bearing...

[Mickeyrouse]

Not familiar with the Volvo raw water flow path, but disconnect the raw water discharge and time the amount it takes a gallon of water to flow directly from the raw water pump as compared to water exiting from the exhaust. Do this while starting from a cold engine so no damage occurs from the two minutes or so it takes to run while measuring and timing.
You’ve checked the thermostat by this time I imagine. Obstructions can appear in the mixing elbow and heat exchanger. It’s also possible other obstructions (barnacles? Zebra clams? impeller vanes?) may have lodged in one of the hoses from some past event but only now settling in some critical spot.
The xchgr can cause problems even if water appears to be adequately flowing. Over time the coolant side can develop build-up. It’s usually a cramped and messy job (aren’t they all?) to remove it and take to a radiator shop for boil-out, but if nothing else works that may be in your future. I would point out that if you have any obstructions in the path of the raw water flow past the point of pump discharge, it is adding to the load on the raw water impeller vanes.
I once had a situation on an engine with raw water cooling that was severely obstructed. It got to the point that impellers were only lasting about 15 minutes.
Regarding the thermostat: Recently our engine was overheating. Suspecting the thermostat, I removed and tested it by placing it in a pot of water warmed to the opening temperature. Worked according to specified temperature. Just the same, I replaced it. Engine now runs “ cool” as a cucumber.

[Mickeyrouse]

Also: the change in engine pitch may be a tell-tale regarding a bearing (alternator, water pumps, engine, loose belts) but it’s hard to imagine though not impossible that it would be so quickly effecting engine cooling.

[Key Wester]

From your pictures, here's what is contributing to your overheat problem.
Those two 90* elbows on the raw water strainer are very restrictive. They should be replaced with straight fittings. These is also a plastic splice in the hose, install one length of marine grade hose that has wire wound construction, so it will not collapse under pump suction.

If you have a strainer outside the hull, replace it with a standard mushroom head thru hull. This will allow bottom paint to be brushed up inside the thru hull. We have also seen c-cocks that look like they are fully open, judging from the handle position, but are actually partially closed. All hose between the ocean and the raw water pump must be marine grade, and of wire wound construction.

Check the raw water strainer gasket for condition. It may be allowing air to enter to system when the engine is running. Also, the raw water pump seal may be allowing air to enter the system, due to it's deteriorated condition. When was the last time the pump was rebuilt? How old is the impeller? Are any impeller pieces stuck downstream from the pump?

Remove the heat exchanger core for cleaning, [ submerge in vinegar overnight] and a pressure test. The exhaust elbow is a maintenance part, they corrode from the inside out. If it is cast iron, and older than 5 years, time for a replacement.

Use 50/50 water and ethelyne glycol [ the green stuff ] for fresh water coolant. Have the FW system and pressure cap pressure tested. Some automotive stores will loan or rent the needed tool.

Is the hull bottom and prop clean of barnicles? Is the prop shaft easy to rotate by hand? If not, you may be fouled on nylon fishing line, which has melted into the cutless bearing and jammed the shaft.

Is there a water heater plumbed to the engine? Most water heaters we see are incorrectly installed, and cause overheat problems.

Check transmission oil, and compare to new oil. Is the oil darker, or smell burned? Are you using the correct oil? The trans may have a siezed bearing, causing the overheat problem.

What engine oil are you using?

Is there a coolant recovery bottle installed? [ very important] Joe D

[Key Wester]

Just remembered a problem we saw with a customer's MD2040. He was returning from Block Island to Providence RI area, when the engine suddenly lost 1/2 it's power. He continued for another hour, and made it home under power, during benign weather conditions. The engine was torn down, and we discovered one piston had split into 2 pieces, horizontally, at the wrist pin.
The engine was rebuilt [Volvo parts are not cheap!] and reinstalled in the boat. Last I heard it was still running. STRANGE type of failure, have not seen that type of failure before or since.

Note that that engine series is a Volvo in name only. The engine was actually built by Shibura in Japan, then Volvo painted it green. The same engine was sold to Perkins, then painted blue. Usually, when a major failure occurs with this engine series, it is much less $ to buy a new engine, than to rebuild the old, obsolete Volvo / Perkins. Joe D

[ebs001]

The first thing to check is the thermostat.

[FULLCIRCLE331]

I have see several problems affecting raw water. Do you a vacuum break? My md2030 has a vetus vacuum break that has multiple size holes it only had the 1/4" open I cut off the small hole and open it to 1/2" much better flow. I only checked this because I had lost an impeller blade. There was a blade blocking the inlet and a blade inside the vacuum break. I have also see the raw water inlet blocked with muscles. I have also see a completely blocked exhaust mixing valve.

[thunderhoof]

The problem I found with my boat's MD2030 after 17 years is that the exhaust/raw water mixer at the output of the heat exchanger corroded through due to action of hot salt water on the cast iron item. The water leakage at that point caused a corrosion buildup thatchoked off the exhaust path and caused a hole to be corroded into the heat exchanger. A pretty mess that required a new exhaust manifold and a new (stainless steel this time) exhaust /water mixer. I recommend you separate the manifold from the mixer and inspect the area.

[Spapkey]

I had engine heating problems. All hoses clear, cleaned the heat exchanger, replaced impeller, .... no joy. I finally replaced the hose from the raw water intake to the raw water pump. .... Problem solved. .... Apparently the hose was old and weakened enough to collapse enough to restrict water flow, but not detectable to the eye. Hope this helps.