D1-30 cannot get above 2000rpm and its not the prop or fuel

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Gavdog

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Hi everyone. This is my first time posting on a forum as I'm desperate and have not been able to find a solution despite multiple boat mechanics and reading loads of forums. My d1-30 is now refusing to go above 2000rpm (sometimes it goes to 2400rpm but then drops back to 2000rpm slowly and then will not go back up). We have replaced the throttle cables, cleaned the folding prop, checked for any prop obstruction but no luck. Injectors have been swapped, fuel lines checked and filters changed, I've even attached tote tank direct bypassing the lift pump and nothing ever changed the rpms at all. Always the same. It should rev around 3200-3400rpm. When I get to 2000rpm the throttle still has room to move but it doesn't increase the revs any further. The mechanics have now given up so I'm open to any suggestions and advice. Thank you!
 
I'm interested to see how this goes. Mine also only gets to 2400 but pushes the boat along at hull speed (7kns) 28ft. Did yours ever get over 3000 ?
 
How many hours has the engine done?

Just an idea:

I suspect there are as many threads on exhaust elbows as anchors :)

Check the exhaust elbow for blockage. I would have thought they would have checked but......

If it is the exhaust elbow then you know the quality of your choice of mechanic.

Its an easy (ish) check. Remove elbow - look inside. it will be very obvious if it is blocked (or almost so). It will look as if its blocked with carbon - but its primarily calcium carbonate (or hydroxide) with lots of carbon pigmentation. As the exhaust elbow progressively blocks it progressively cannot reach full revs - but will happily tick over. It varies with the seawater chemistry but 1,000 - 2,000 hours is the issue.

If you use the search function and key in 'Exhaust Elbow and MM5AHO' you will find Geoff made a fully documented thread with pictures of exhaust elbow remove.

You can clean with acid (but ask here for more information) or buy a new one. There seem to be reasons to dispense with Volvo elbows (apart from the fact they are extortionate) and buy one made of stainless - as they do not corrode quite so quickly. Again raise another thread here.

And

Welcome to the forum!

Jonathan
 
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Welcome, all of what the others have stated, but the revs you mention, is that in gear, or in neutral? If it's in neutral, would that point to the governor?
I've no idea about this particular model of engine, and this is pure conjecture from a total non-expert. (y)
 
Your details are rather brief so as Jamie has asked we need to know if this happens both in gear and neutral. The other thing that even your questionable engineer might not have done is to check and confirm to us that when you move the throttle lever in the cockpit to full speed that the connected governor speed lever on the engine replicates the FULL travel and hits the full speed stop. If it doesn't then disconnect and move it towards the full speed stop when running to see if you get full speed . If the speed lever on the engine goes to the full speed stop and the engine does not rev up to full speed in neutral then it is a governor issue. Possibly a broken or damaged spring.

If the speed lever was not moving all the way to full speed then you have to make adjustments to the mechanism at the cockpit end and move the Teleflex connection to the speed control to a hole further along the lever from the pivot to give the Teleflex more travel.
 
I had exhaust issues with my last engine, as someone said, used to smoke white. Tried all sorts til someone asked if I looked at that. Got a stainless one the difference was remarkable. Turned out it wasn't smoke but steam ?
 
Neeves said:
How many hours has the engine done?

Just an idea:

I suspect there are as many threads on exhaust elbows as anchors :)

Check the exhaust elbow for blockage. I would have thought they would have checked but......

If it is the exhaust elbow then you know the quality of your choice of mechanic.

Its an easy (ish) check. Remove elbow - look inside. it will be very obvious if it is blocked (or almost so). It will look as if its blocked with carbon - but its primarily calcium carbonate (or hydroxide) with lots of carbon pigmentation. As the exhaust elbow progressively blocks it progressively cannot reach full revs - but will happily tick over. It varies with the seawater chemistry but 1,000 - 2,000 hours is the issue.

If you use the search function and key in 'Exhaust Elbow and MM5AHO' you will find Geoff made a fully documented thread with pictures of exhaust elbow remove.

You can clean with acid (but ask here for more information) or buy a new one. There seem to be reasons to dispense with Volvo elbows (apart from the fact they are extortionate) and buy one made of stainless - as they do not corrode quite so quickly. Again raise another thread here.

And

Welcome to the forum!

Jonathan
Click to expand...
Thanks for the thoughts. Yes it has a stainless steel elbow already and was checked by the mechanic who said it looked fine. It has high hours (5500) and was rebuilt/reconditioned a while back before I bought it. It seemed to change straight after one of the mechanics was working on it but that may have been a coincidence and he had no idea what he could have done
 
neilf39 said:
Also check for a blockage in the fuel line, assuming you have changed the fuel filters. Diesel bug or bits of rust off the tank could be restricting the flow.
Click to expand...
Cheers but definitely not fuel as I bypassed everything using a tote tank straight past filter and lift pump to injectors and exactly same revs
 
jamie N said:
Welcome, all of what the others have stated, but the revs you mention, is that in gear, or in neutral? If it's in neutral, would that point to the governor?
I've no idea about this particular model of engine, and this is pure conjecture from a total non-expert. (y)
Click to expand...
Thanks for the thought. It's in gear that it can't get the revs. In neutral it goes up to 3400rpm fine
 
Bilgediver said:
Your details are rather brief so as Jamie has asked we need to know if this happens both in gear and neutral. The other thing that even your questionable engineer might not have done is to check and confirm to us that when you move the throttle lever in the cockpit to full speed that the connected governor speed lever on the engine replicates the FULL travel and hits the full speed stop. If it doesn't then disconnect and move it towards the full speed stop when running to see if you get full speed . If the speed lever on the engine goes to the full speed stop and the engine does not rev up to full speed in neutral then it is a governor issue. Possibly a broken or damaged spring.

If the speed lever was not moving all the way to full speed then you have to make adjustments to the mechanism at the cockpit end and move the Teleflex connection to the speed control to a hole further along the lever from the pivot to give the Teleflex more travel.
Click to expand...
Thanks heaps for taking the time to reply. It's in gear that it won't hit the revs. When I move the throttle I can see the lever going the whole way down next to the idle adjuster if that's what you mean. I believe both mechanics (I've had 2 very experienced ones look at it) checked the throttle range. When I move the lender in gear, it gets up to 2000rpm and then the lender continues to go forward but revs stay at 2000. When I first statlrt engine I can usually get 2500rpm but over next 5 mins it comes down to 2000rpm on its own
 
P
Gavdog said:
Thanks heaps for taking the time to reply. It's in gear that it won't hit the revs. When I move the throttle I can see the lever going the whole way down next to the idle adjuster if that's what you mean. I believe both mechanics (I've had 2 very experienced ones look at it) checked the throttle range. When I move the lender in gear, it gets up to 2000rpm and then the lender continues to go forward but revs stay at 2000. When I first statlrt engine I can usually get 2500rpm but over next 5 mins it comes down to 2000rpm on its own
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Ps, in neutral it hits 3400rpm
 
Gavdog said:
It seemed to change straight after one of the mechanics was working on it but that may have been a coincidence and he had no idea what he could have done
Click to expand...

What was he working on, and did he disonnect/reconnect any bits in doing whatever it was?

Can you turn the shaft by hand with little resistance?
 
Pye_End said:
What was he working on, and did he disonnect/reconnect any bits in doing whatever it was?

Can you turn the shaft by hand with little resistance?
Click to expand...
He put serviced injectors back in. Same revs so then swapped other engine's injectors to check but no change at all.

I've checked for prop obstructions but snorkel and have cleaned it to no avail. No change at all. Exactly and revs. Prop shaft seems to spin same underwater as other d1-30 engine which revs to 3400.
 
hi and welcome,
haven't mentioned anything about the hull (or missed it!)
when was the hull last cleaned? after a winter in the water, mine now wont do more than 1500rpm (2700max) due to growth
 
You mention that you have a stainless elbow and appear to dismiss the idea that it might be blocked.

Has it been checked.

Checking would take maybe 15 minutes.

I am aware that a few members here have swapped from a cast to a stainless elbow. I can fully accept that a well made stainless elbow will reduce the problems of corrosion in the Volvo cast elbows. However it has never been clear if a stainless elbow is not subject to the calcium build up and blockage of the cast elbows. To put it another way - the calcium build up is a function of the elbow being cast - or its going to occur in any elbow.

I have never seen anyone comment on calcium build up, or not, on stainless elbows - but have not made a specific search.

Jonathan
 
vas said:
hi and welcome,
haven't mentioned anything about the hull (or missed it!)
when was the hull last cleaned? after a winter in the water, mine now wont do more than 1500rpm (2700max) due to growth
Click to expand...
Hull has been cleaned and the other sides engine gets to 3200rpm so it's definitely not the Hull. Thanks tho
 
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