Volvo D2 75F Waste-gate stuck

[DDW]

When/if I complete the conversion, I'll post back. It isn't a singular problem, lots of people with the same problem posting on various forums.

[skipperpete]

Apart from the obvious Volvo stupidity with the actuator hitting the casting boss your wastegate gets stuck because of the pool of raw water sitting in the aqualock a couple of feet away. Your turbo scroll and exhaust valve stems suffer the same fate and occasionally engines are seized by a build up of corrosion on the walls of whichever cylinder has an open exhaust valve after shutdown. It could be worse, Volvo decided to go one better with the VNT turbo and the humidity from the wet exhaust very quickly renders the nozzle rotation imperative and useless after a period of layup.
If you’re worried about the effects of a stuck waste gate you could install a BOV ....available at most auto supply outlets rather than ditch the turbo entirely, .....and I guess that’s what you already have when the boost pressure pops off the intake manifold hose....

[ohthetrees]

Great stuff DDW. I'm intending to do this conversion next time my turbo acts up. I cruise far from civilization where fuel economy really matter for my range, so I don't think running at >2000 rpm to keep the turbo happy is really a viable option.

[DDW]

I generally run between 1800 and 2200 rpm, very occasionally 2400 if I am in a great hurry. I should have specified the D2-55 from the start.

I don't have any interference problem with the wastegate lever, but it does freeze up after even a fairly short layup. While we can fault Volvo for placing their marine engine in close proximity to salt water, what else are you going to do in a boat? It isn't exactly a unique-to-Volvo issue: talking to the turbo rebuilder, he says it is quite common in many marine engines and keeps him in business. The turbocharger was designed and built by IHI, same as the engine.

I think the main design problem here is that the turbocharged version is more appropriate for engines run hard and often, or in applications where the throttle is varied a lot (like a tractor or loader). Problematic on a boat, especially a cruising sailboat.

[DDW]

A little update on this. Investigating the parts needed to convert from 75 to 55, beyond the injection elbow (which I would buy aftermarket from HDI) there are two hoses and the inlet adapter (between intake manifold and plastic intake silencer box). The air filter and inlet silencer box are the same, on the 55 is it rotated 90 deg relative to the 75, a different bolt and spacer are used. However the inlet adapter does not have a part number in the exploded diagram of service parts. It could be easily fabricated, I have the Volvo dealer looking into availability.

There are two hoses, water pump">raw water pump -> heat exchanger and heat exchanger -> injection elbow. These are molded hoses and very expensive at $139 and $188. You can probably use generic hose but it will not be neat.

The oil feed to the turbo is a diamond shaped plate with an O-ring recess, I will machine one but you could use the existing and block the tube. It is under oil gallery pressure and you don't want it to leak. The return is also a diamond plate, but no pressure and just sealed with a gasket.

The exhaust hose will have to be adapted from 2 1/4 (an unusual size) to 3 1/2. No one seems to make that adapter so it will need to be fabricated.

I have also experimented a bit with the wastegate. The turbo still functions on my engine, but the wastegate is stuck - I can move it with some effort and a wrench, but it is not operable with the servo pot. I've tried running with the wastegate open without any seemingly detrimental effect. An inherent characteristic of boat propulsion is that the engine available (max) torque curve greatly exceeds the prop absorption curve at any rpm except the maximum. The engine torque curve flattens and then drops near max rpm, the prop absorption curve rises to meet it. The waste gate on a turbo on the other hand, is designed to close and increase boost and available torque at lower rpm (where it is not needed on a boat), and open to limit boost at high rpm. While a wastegate serves a valuable purpose on a tractor (where low rpm torque is of use) it seems to serve little purpose on a boat - the extra torque it provides at less than max rpm cannot be used without changing the prop. If the turbo were correctly sized to produce the called for maximum boost at max rpm, then no waste gate is needed.

I intend to measure the boost pressure with the wastegate stuck at various positions, mainly fully open and fully closed. There are many reports of overboosting with the wastegate stuck closed, so that is probably bad. But the published boost curves at max output show it limiting at 8.7 psi @ 2000 rpm, suggesting that the waste gate begins to open there and must be well open at 3000 rpm with 50% greater exhaust flow. Note that on a boat, the torque needed to turn a correctly pitched prop at 2000 rpm will be well below the maximum (less than half), fuel and exhaust flow will be limited by the governor to what is required, and the boost will not reach that value in real operation nor is it needed. This in turn suggests that the engine will perform to spec (when connected to a propeller) with the wastegate fully or mostly open at all times.

[Capt123]

Wow guys
I learned a lot reading you !
I have a Boréal 44 with the D2-75 engine and of course the waste gate valve stuck for may be many years.
The engine is 10 years old and was not maintained until I bought it one year ago. I will change whenever possible the exauhst elbow for a SS one and try to clean or free the valve mechanism.
Thank you for your advices !

[Gedimin]

I'm having this famous oil leak from the breather now ... my usual cruising RPM in 2000-2100, guilty of not exercising it much higher.

Just to reiterate:
- how do I know if the waste gate is stuck?
- at this point, with a small leak, shall I try revving full throttle to burn soot and reduce the leak? Or is it too late and I will make the leak worse?
- what's the best cure without replacing things? Remove turbo, clean it, put back and then do max revs for a minute every hour of motoring?

[DDW]

Easiest way to see if the waste gate is stuck is to move the waste gate lever going into the turbo. Just put an open end wrench on it and attempt to turn it as though the waste gate pot is pushing the push rod (as it does under pressure). It should turn fairly easily and spring back. If it doesn't turn at all, or you can turn it and it with some effort and it stays, then it is stuck.

The oil blowing out the breather hole in the intercooler? This is normal for this engine. Mine did it from new. I've had lots of people tell me it is normal. Rebuilding the turbo did not change it. Not good, but normal. I finally dealt with it by taking a small aluminum baking pan, strapping it in place behind/under the hole, and putting some oil absorbent pad in there. It really isn't very much oil, but when there is boost, it is spraying a bit out the hole and makes a mess.

[Gedimin]

I had a Volvo engineer over here and he concluded that it was the waste gate. The engine was serviced before winter, but then the waste gate should have been exercised after going into water. After 4 months ashore it was stuck.
The engineer unblocked it, but it still leaks. Not massively like before, probably ten times less (before his visit I was losing 50-100ml per day!).
I tried to wiggle the wastegate myself - it only rotates about 5 degrees, is it right? Or is it semi-stuck again?
If I wanted to resolve it for good at some point, would taking the turbo off and proper cleaning help?

[DDW]

It only moves through a small angle - maybe 10 degrees. If it is loose enough to move, you can feel it hit the ends of travel.

Unfortunately, this will be a temporary fix. You can remove the turbo and at least them you can see the waste gate valve, but the shaft is welded on both ends, to the valve and the other to the lever that operates it. There are kits to fix it, but it involves cutting the old one and welding the new one once installed.

It is just a bad design for intermittent use.

[silvercreek]

Originally Posted by DDW

Easiest way to see if the waste gate is stuck is to move the waste gate lever going into the turbo. Just put an open end wrench on it and attempt to turn it as though the waste gate pot is pushing the push rod (as it does under pressure). It should turn fairly easily and spring back. If it doesn't turn at all, or you can turn it and it with some effort and it stays, then it is stuck.

The oil blowing out the breather hole in the intercooler? This is normal for this engine. Mine did it from new. I've had lots of people tell me it is normal. Rebuilding the turbo did not change it. Not good, but normal. I finally dealt with it by taking a small aluminum baking pan, strapping it in place behind/under the hole, and putting some oil absorbent pad in there. It really isn't very much oil, but when there is boost, it is spraying a bit out the hole and makes a mess.

Mine leaks oil from new, in addition to coolant. I lose about 1oz of coolant every 3-4 hours of engine run time as a result. I also noticed my wastegate is stuck closed.

Any theories on how coolant could end up coming out of the turbo/aftercooler weep hole? I assume I've been WAY over-boosting the engine, as I do occasionally take it to 3000RPM... perhaps the excessive boost pressure is pushing coolant somewhere it shouldn't be?

Worst case would be leaking head gasket, though there are no signs of coolant in the exhaust or anywhere else other than the weep hole on the back of the aftercooler. Engine runs strong.

Lots of corrosion on the exhaust elbow and also the bottom of the turbo. I have a new SS elbow en route and will replace it. I'm thinking perhaps I should replace the turbo assembly as well.

Engine is only 3 years old with 250 hours.