Another thing to watch on the D4 engine

[Hydraulicjump]

We all have to be vigilant in paying attention to our engines, but sometimes we don’t know what to look for. I had a good mechanic schooling me the other day, hopefully with a good outcome.

Pacific Power in Seattle sent a great mechanic to do a standard service and coolant change on our Volvo Penta D4-260. While he was working on it he called me to look at something I had seen, but not paid attention to. There was a collection of white salt crystals on the front of the charge air cooler—that large green rectangular box with fins on the port-side rear end of the engine. I think the rest of us call it the intercooler. This connects to the raw water pump and helps cool the engine with seawater.

The crystals were formed at the contact between the main housing and the cover that connects to the raw water pump hose. It was clearly a leak that was precipitating salt. And closer inspection showed that the leak may be starting to drip on the starter motor, which can only end badly.

So check for white salt crystals on all the connections between the raw water pump and the charge air cooler. This may be a sign of trouble. And, as in my case, be sure to check this before your five year warranty is up! This is a very expensive fix that takes three days.

Jeff

 

[olygirl]

Thanks for this information! I will look at our engine tomorrow. Here's another thing to ponder...I have noticed a (new) sound recently when underway. I hear a high-pitched rattling sound that I haven't noticed before. It doesn't occur at low speeds, only when doing around 3000+ RPMs. Everything appears to be normal as far as all of the engine readings go and there is no problem with overheating or anything else that I can tell. Maybe it's just the engine getting "settled in" and it's a normal thing. We only have around 220 hours on the engine. Am I worrying about nothing? Appreciate any thoughts.

Thanks!

 

[Hydraulicjump]

Ohh. The experts will have to weigh in on that one. Try lifting your engine hatch to see if the sound is coming from the engine first. But this is a reminder that a good mechanic is both problem solver and therapist. Cultivate them. They are a dying breed and hard to find.

 

[bvankeppel]

Something completely different. I started hearing a rattling sound which appeared to come from the engine, also at higher RPM's (2900+). Could not find it, engine hatch open or closed, till finally I realized it was the transom door that rattled, which it did not do before. A little piece of rubber and the problem gone. I realize this may not be always be the case, but rattling noise is tricky.

 

[Headlee]

Could you provide a little more information on the salt crystals? Are the crystals the result of poorly fitting hoses or gaskets allowing small amounts of saltwater to seep out and crystalize? Or, is there something, such as the starter replacement that would result in the expense and three-day repair? Thank you.

 

[Bobby P.]

Whenever you hear something “different” never assume it might be normal. That type of coaching and self talk has more than once lead to more expensive problems. Keep digging until you figure it out. Many times it is a minor thing that could grow to a major thing. Most recently while lazing around on a calm and peaceful afternoon safely anchored, I heard a soft knocking. It wasn’t obnoxious or very concerning. I was thinking it was the water lapping up against the chines of the boat. I fell asleep for a 15 minute nap. When I got up, the soft knock was still occurring. When readying the boat to move, I went to pull the dink and found the source. My weaver mountain bracket one the dink had been softly ready being up and down on the side of the hull for several hours.

- Lesson learned!

Hopefully you will find the source. The one that has gotten me several times has been the high pitch whining sound that occasionally is coming from the engine room, but turns out to be one of the fishing poles whistling in the wind. Hope yours is similar.

Good luck digging!

Bobby

 

[BB marine]

The air cooler and heat exchanger both D4 and D6 are both inspection points. The end covers use O-rings as seals. Theses areas over time tend to leak. The leaks are not always seen. The leaks normally happen when the engine is operating at full temperature. The expansion of the coolers from the heat open the split lines up. The leaks are minor but over time cause damage to the matting surfaces. The leaks are notorious for damaging the starter motor. When inspection is done any signs of corrosion at the split line is an indicator that there is a leak. Removing both exchanger and cooler should be a 1000 hr inspection, clean, pressure check and reinstall or every 5 years if the boat and engines are operated in salt water. Or if there are indications of a leak. When servicing the cooler and exchanger the reassembly should include a clean mating surface and the use of a good anti-corrosion grease coating Both surfaces and the O-ring.

 

[Headlee]

Thanks, Brian, for additional information. I've seen salt residue around the hose near the impeller, but now noticing a small amount on the cooler. I have 380 hours on the D4, but it is now six years old. I'll talk to my tech about this during the fall haul out and maintenance.

 

[gswearin]

Hi Brian, do you have a list of "inspection points" or are they points the experts look at in annual maintenace?
OlyGrl I don't have a high pitched "rattle" but I do get a high pitched noise, sounds similar to an alarm right around 3150 RPMS. This has been from day 1 and Ranger and the Volvo tech both said it was the turbo acting normally (never heard an engine noise like it).

 

[Cutwater28GG]

anybody have photos of what is being discussed here?