Volvo D4-300 low RPM's

[harbournate1]

Recently took our R31CB out for a cruise and was unable to go over 1800 RPM's. No alerts or warnings and all gauges were normal. Called in our local Volvo tech to troubleshoot and he found that the turbo was siezed. He has seen this before and it is apparently caused by minimal elevation between turbo exhaust elbow and water line in the wet exhaust. This causes condensation to form in the turbo and it reacts with the buildup on the vanes and causes corrosion which causes the vanes to stick. This same situation has been mentioned on this forum as having caused water ingestion to the engine. According to Fluid Motion the engine installations are all reviewed by Volvo and deemed adequate. It seems that if that were the case that this would not be a problem. This is the 3rd turbo on this boat and now it has to be reconditioned (hopefully).

Has anyone come up with a solution to this problem?

 

[BB marine]

The Turbo turbine wheel seizing on the D4's installed in Ranger 29 and 31 seems to be a common complaint. There have been several threads about this issue and I have also spoken to a number of Tug owners that have had the issue with no power and no boost. I will agree that the engine installation is marginal to Volvo specifications. I had the installation manual in PDF form for the D4 and D3. When I had my C26 Cutwater (D3) I went through the installation and found a few of either marginal or did not meet specification in the install. I contacted Fluid Motion and the response was the install was approved by Volvo.

In my case the exhaust hose across the transom was installed lower than specification and had no fall to it for overboard discharge. Basically all water would flow back to the exhaust muffler can after engine shut down. The Riser elevation meets specification but marginally. The safe elevation for a riser discharge should be 12" above the water line.My C26 was 8" or less depending on how the boat was loaded. I will say that when I pulled the Turbo for replacement it did not show water damage. My biggest issue was Heat because of no engine room Ventilation. Fluid Motion did not read the manual when it came to that. There is virtually no ventilation for that compartment except the gaps and crevices between the cockpit liner and the hull??? This too causes condensation and moisture. Look around in the compartment I guarantee you will see black mold.

The riser elevation is a issue but I believe the biggest culprit with the Turbo in the D4 is it needs to spin up frequently. If the normal cruising is done below 2100 rpm the turbo is not working and it gets coked up. Most of the build up is coke from the exhaust and lower exhaust temperatures from not running the engine frequently in the torque curve at or above 2200 rpm to 2800. Even though this engine is common rail it can still foul especially when it is a 3.7L displacement engine putting out 300 hp.

There is not much you can do about the install. When you get a refurbished turbo, spin it up maybe once a day while cruising for a few minutes to get the exhaust up to full temperature to reduce moisture and clean the coke build up.

My opinion, Listen to the Volvo tech he is the one that has eyes on the issue.

 

[mlanger]

At the Rendezvous last year, the Volvo guy doing the presentation made a point of telling us that the engine “likes” to run at 80% to 90% RPM. That puts my D4/300 well over 2000 RPM. (I think max RPM is about 2450.) I’m wondering if this is one of the reasons he made that recommendation.

 

[glider4]

MLANGER,
Either the D4-300 is very different than our D4-260 or you may have a typo in your max RPM number. Our D4-260 has a max RPM of 3,500 and a recommended max continuous RPM of 3.250. The 90% max RPM number would be 3,150 and the 80% max RPM is 2,800.
We typically cruise at 2,750 to 2,850 RPM due to the swim platform on our C-28 being awash at RPMs above 2,900. We do short runs at 3,100 RPM or higher at least once a day to keep the turbo clean. At 2,800 RPM we are getting about 2.0 to 2.2 MPG but we are typically pretty heavy on our cruises.

 

[bemiller75]

I had this problem after wintering on the water with my D4-300. The techs I hired (I was down with COVID) told me I needed a new turbo. I fired them. The fix is fairly simple on the R31, based on advice from the expert who sold me the boat. I pulled the exhaust elbow off the turbo housing and spun it out of the way, sprayed the turbo with solvent (PB Blaster), let it soak in, and then started trying to rotate the turbo blade shaft gently with a socket wrench to free it from the carbon that had frozen the blade (I used a 12 pt metric socket). After about 30 minutes or so, I got the blade free enough to rotate a full 360 degrees with some resistance. I sprayed on another dose of PB Blaster, and let it set overnight. I came back the next morning with my socket fixed to a power drill, and started rotating the turbo blade, slowly at first, with the power drill. After a few minutes of this at increasing speed (both directions), the turbo blade was entirely free spinning.
Sea trials were entirely successful.

 

[Gin]

Interesting way of handing the turbo issue!

At WOT, the D4-300 should be at about 3600 rpm. Substantially more than the 2450 mentioned by one of the earlier posts. 80% to 90% should then be about 2900 rpm to 3200, give or take a bit.

Gini






4

 

[BB marine]

Testing to confirm WOT is a good practice. This shows good Turbo output, good fuel input, and manufactures recommendations are being met for good engine longevity.

A good practice is to know what normal boost pressures are at different rpms. Knowing where boost starts (RPM) , boost # for the high torque rpm which is around 2500 rpm D4, WOT boost pressure. Having theses numbers gives the captain an idea of the turbo performance and if there are issues before the turbo cokes up or fails entirely.

Diesels like to run in the high torque curve area. This range is where the pulling power is. Exhaust temperatures good, clean burn good, and power to push the boat through the "HUMP" is all achieved in this operational area. I don't think you will have coking issues if you run all the time and this Rpm range is probably around 50% load. The problem, this is not an efficient speed to operate the boat especially a Ranger tug. This is the stern dig speed.

With common rail engines operating at below high curve rpm is normal and is where the best fuel economy can be found. It is not going to hurt the engine running there but there should be a routine of throttle advancement to get the engine working and operating at higher loads to heat things up and clean the exhaust and raise oil temperature to reduce condensation. This really holds true with all diesels. I just finished the Loop with a pair of 4LHA direct injection mechanical engines. Theses engines are not as clean burning as a common rail engine. The engines like to run in the 2600 to 2800 rpm range. In my boat that is about 18kts and 1.25 mpg. Doing the Loop at this speed was not our choice. I did at least 75% of the trip at 1450rpm 8kts. Many told me you will not be doing the engines favor running like that!!! I changed the oil every 150 hours and sent each oil change into Black Stone. All reports were perfect even the fuel % in oil was below average. The engines would climb up to full recommended operating RPM when ever the sticks were pushed down. The turbo boost was alway constant. I did push the engines every couple of days to heat them up Exhaust and oil. The one element that is very constant with my boat and engines is operating temperature. It has a large raw water cooling through hull and strainer. The engine temperature fluctuation between idle (after engine is at operating temperature) 175F and WOT is 5F. The engines will never go above 180F even if I hold the throttle to WOT for 10 or 15 minutes. ( I have never run them for more than that) My point, Run your D4's up and clean them out. This does not mean WOT it just means at or above the high curve.

(harbournate1) good luck with your repair and share your findings once the engine is operating correctly. This is good information to share to D4 owners.

 

[YukonRon]

I had this discussion with the Volvo Penta rep doing the seminar at this year's Roche Harbor rendezvous. He made the usual statement about needing to run these diesels up to high RPM regularly to get the operating temperature up.
After the seminar I had a chat with him, and told him how our D4-260 almost always runs at a consistent 185 degrees, regardless of RPM; except possibly when I do a WOT run it can hit 190. I only do that occaisionally and briefly to test the top end.
His response was: as long as you are running in the normal operating range of 185 degrees, it doesn't really matter what RPM you are running at.
This is measuring the engine operating temperature, but we didn't get into a discussion about how/if that might relate to the turbo.

 

[Miss Stress]

A diesel engine has three temperatures to consider. Water temperature, oil temperature, and exhaust temperature.
The recommended WOT operation on a regular basis will help immensely with turbo contamination and carbon buildup, both in the turbo and the compression rings / grooves.