AQ 145 Engine Revs

[Enterprise6]

Hello all

I have princess 30DS running twin volvo AQ145 petrol engines. On a recent trip to the tidal thames the first we have done I noted that the port engine would not rev over 3000 rpm and the starboard engine pulled about 3250 but wouldnt exceed this. When both engines are out of gear the rev freely.

I dont think this is not a major problem for us as most of our boating is done on the non tidal thames with engine reves rearly exceeding 1800 (unless im damaging the engines of course) but just wondered why this would the engines not rev higher?

Thanks for your assistance

 

[Spi D]

If one engine refuses to go over 3000, all the work above that is left to the other engine. It won't cope with that but at full struggle it reaches 3250.

This puts an extreme load on the poor thing and really should be avoided.
Ofcourse you could go around 1800 and pretend that everything was fine, but 3000 rpm on that engine is a sure sign of something being wrong.

Your engines should run the same and reach 5500 rpm at WOT provided your hull is clean, your load is normal and your propellers are undamaged. As only one engine seems bad, the hull most likely is not the issue.

If all else OK and it still does not perform, things should be investigated. Start by checking fuel supply (filter, carburettor working?) and ignition (plugs, timing, leads).

 

[Davy_S]

After having problems myself with an AQ145B, I would check as sugested, plugs, leads, carbs, filters etc. then the props, cleanliness of hull need to be checked. Our problem was timing and advance /retard, on this engine they are critical. We found that the springs on the advance retard had disintigrated (bobweights in old money) You need to get a strobe and fully check the timing, from recolection (vague) the advance timing was 19 degrees btdc. This makes an amazing difference to performance, also these engines have been known to be out on the timing belt by a couple of teeth.
The engine should reach over 5000 rpm at WOT, if not, you need to sort it out before other problems arise.

 

[Spi D]

In case you have no owners manual, get it here:

http://vppneuapps.volvo.com/ww/PIE/...403&d=Owners Publication&s=5258293&lang=sv-SE

Ignition and other info is on page 18.

 

[Enterprise6]

Thank you I will look into these things and report back. Just one thing as both the engines rev upto 5500 when out of gear could this possibly suggest a problem with the legs/props

 

[Spi D]

No.

To perform under load the ignition timing advance is absolutely neccessary. With no load it'll rev no problem as it does nothing but spin.

If you do begin with the suggested investigations, you may soon have a solution. Distributor parts are among the less expensive on an engine, so go ahead

 

[Peanuts]

Hi

I see from your post that most of your boating is plodding along slowly. When did you last have a chance to open up the engines,where they OK then? Have you even had them going fast before? Could even be the wrong props. It would be interesting if you had the prop sizes/pitch.

My first port of call would be to ensure bottom (of boat) is clean, then the props. Only then after testing would I be looking at the engines if I didn't get an increase in RPM.

 

[boatone]

I have princess 30DS running twin volvo AQ145 petrol engines. On a recent trip to the tidal thames the first we have done I noted that the port engine would not rev over 3000 rpm and the starboard engine pulled about 3250 but wouldnt exceed this. When both engines are out of gear the rev freely.

I know this seems a long shot but try calling Princess and see if they can dig up a delivery trials report for when the boat was built. I did this with my Hardy and was surprised to find they still had it on file and very useful info too.
Not only did it record performance figures but quite a lot of other useful info including engine serial numbers as well as prop sizes and speed at various rpm.

Also it is quite possible your boat has been over-propped for use on the river which is particularly good at slow speeds but will result in the top revs being much reduced. On mine the max revs with the correct props would be 4,400 but because I am overpropped this drops to about 3,500.

 

[Enterprise6]

Thanks one and all

The bottom of the boat is clean she was lifted and antifouled in May/June this year.

This was the first time I had ever the opertunity to opened up the throttles since Ive owned the boat. I will try to find out the prop size, it may be as has been stated the she is over proped for river usage

 

[Spi D]

Thanks one and all

The bottom of the boat is clean she was lifted and antifouled in May/June this year.

This was the first time I had ever the opertunity to opened up the throttles since Ive owned the boat. I will try to find out the prop size, it may be as has been stated the she is over proped for river usage

Yes, but even so they should run equally. Fitting way too high pitch props would make it go pretty fast at idle - do you experience that?