Advice Needed for Twin Engines

[Dave_Seager]

I have many years experience with single engines and am now planning to switch to twins. I am looking at boats around 30 years old with diesels such as Perkins 4.108 or Volvo AQMD32A.

I am not sure how closely matched I should expect the maximum r.p.m. to be between the two engines. Any suggestions?

Thanks,
Dave.

<hr width=100% size=1>Dave Seager
Weybridge UK

 

[dignity]

This in only my opinion but leave Volvo AQD32's alone nothing but trouble.

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[Talon]

Your question confuses me, have you looked at a boat and found that the RPM does not match up? Or is this in anticipation of a boat you are about to look at and you feel this could be an issue?

RPM is measured on a gauge, if the gauges are out, then no the RPM will not match. I tend to set my engines by feel in the boat, you get a distinct throb if the revs are off slightly from each other and the speed of the throb gets slower and more drawn out the closer you get the revs to each other, a bit like tuning a guitar. On our boat, from the flybridge, generally having a throbless smooth setting does not normally display the same RPM on each gauge. This does not bother me in the slightest though.

Also, why not Volvo 32's, I am interested in common problems on these. We have the 31's./forums/images/icons/smile.gif



<hr width=100% size=1>Alex

<A target="_blank" HREF=http://www.mad-als.com>http://www.mad-als.com</A><P ID="edit"><FONT SIZE=-1>Edited by Talon on 17/02/2004 14:23 (server time).</FONT></P>

 

[apollo]

In my opinion, stay away from Volvos full stop.

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[scottie]

old 32 6 cyl peugot based are difficult to get spares for

later 31 and kad32 are totally differnt engines

any boat with 30year old engines must be lokked at carefully


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[Moose]

Why?


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[apollo]

Extortionate parts prices, poor reliability compared with other makes.

I have had Volvos in the past, then Thorneycrofts on previous boat, now have Mermaids and would never go back to Volvos.

I know there will be a few that will come on here and bleat how good they are - fine, you stick with them, I'll stick with something Ford-based.





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[dignity]

The old 32's were notorious for blowing head gaskets.

Quick question I've just bought a boat with TAMD31's seem to give off a fair amount of white smoke when cold, do yours?

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[martynwhiteley]

My last boat had twin 4108's of about 20 year vintage, although they had been reconditioned not too many years before I bought the boat.

They went ok once running, although would only start from cold in winter with the assistance of 'easy-start' despite the (crude) fuel heater system employed.

One unit never rev'd as high (according to the guages) as the other, although as already queried/advised, this is not a significant issue, and you just 'use the force' to balance the revs. (Not that you'll have much joy in outrunning Darth Vader, as I never got more that 7 or 8 knots out of the P25 (unless running the tides)).

The biggest problem with 4108's is noise, and despite insulating all surfaces of my engine room with the best material available in thicknesses that left little room for anything between, the boat was still uncomfortably noisy, to the point of spoiling the enjoyment. Comparing this to my new D120 is chalk and cheese.

<hr width=100% size=1><font color=blue> <A target="_blank" HREF=http://www.mboat.org>http://www.mboat.org</A></font color=blue>

 

[Alistairr]

Have you not got work to be getting on with????/forums/images/icons/laugh.gif/forums/images/icons/wink.gif



<hr width=100% size=1><A target="_blank" HREF=http://arweb.co.uk/argallery/alistair?&page=1> My Pictures, Look if you want.</A>

 

[martynwhiteley]

Yes, but the small of diesel was permeating from the forum.........


...........Oh, go and deliver a few tables /forums/images/icons/smile.gif



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[Talon2]

Hi Dignity. I am Talon 2, Alex is my son - we jointly own the boat. Yes we have smokey 31's. They need to get right up to working temp before they will stop. We have had the injectors cleaned, this was done by a local injector company. However we have been told that only a specialised Volvo workshop can undertake this because the injector jets are much smaller than normal vehicle diesel engined jets. However a Volvo engineer told us that if the engines reach there max revs of 3,800 there is not going to be any problem with the injectors. We also get a layer of black soot on the stern of the craft after a long cruise. When we mention this to Volvo we are told that the 31's were notorious for this and there is no real remedy. We have come to live with it by starting the engines and moving quickly out of the mooring or at least wait until we are up wind and the smoke goes over the yachts behind us!!

<hr width=100% size=1>Keith

<A target="_blank" HREF=http://www.mobiledit.co.uk>http://www.mobiledit.co.uk</A>

 

[franktheseadog]

I had a pair of Volvos on a 30 foot Scandinavian GRP thing and they were nothing but trouble. They had done 500 hours when I bought it and I was assured diesel engines like these would go on and on. Total crap they were. Clouds of smoke. Spent two grand on new injectors. More clouds of smoke. Crazily expensive parts. I would never ever touch Volvo diesel engines again... unless they were brand new and money was no object.

<hr width=100% size=1><P ID="edit"><FONT SIZE=-1>Edited by franktheseadog on 18/02/2004 07:52 (server time).</FONT></P>

 

[miket]

You say AQMD32? This is an outdrive version of the MD32 I believe.

Be very careful taking on a 30 year old boat with outdrives unless they have been recently replaced. With this age of boat, in my view, you are much better advised to go for inboard engines and shaft drive.

I had Ford Thornycroft 108 hp engines in an early 70's Freeman 32 and apart from being a bit leaky (oil and water) they never gave any trouble.
I never worried too much about matching rpm. If it got close that was fine!!

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[BarryH]

I've read the replies to your post. The one thing I would say is take what you read with a pinch of salt. These are peoples opinions, nothing else. Some based on fact altho in reality very few. Some based on secondhand experience and some on hearsay. Some are total bollox, scuse my french.
With any boat engine of that age, beit a Ford, Perkins or even volvo. It depends on how the thing has been looked after. Does the owner look like the sort of person who keeps up the sevicing or not. Has it been carried out when it should have been. I'm always very weary of boats for sale that have just had the oil changed. Very iffy if you ask me. I'd rather see that it was changed when it should have been and not just before it was put up for sale. Boats that are just seviced before selling probably get serviced at that time only!
The volvo Aqmd 32 is based, as said, on the old pug 6 poy lump. You CAN still get reasonably priced spares for them. They DONT blow head gaskets at the drop of a hat. That is normally due to a ham fisted spanner monkey who doesn't know how to use a torque wrench on an ali headed engine.
As far as the spares costs go. Buy them from a marine dealer and you pay marine prices. Go to a GOOD local factors and you'll get the stuff at reasonable prices.
Thirty year old engines won't be perfect, you'll probably need to spend a few quid on them here and there. But you are looking at 30 year old boats so to expect to buy something in perfect condition is expecting a bit too much really. Have fun looking though!

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[pheran]

Bit cheeky BarryH

Dave

<font color=blue>The one thing I would say is take what </font color=blue>Barry H <font color=blue>says with a pinch of salt. This is his opinion, nothing else. Some of it may be based on fact altho in reality very little. Some of it based on second-hand experience and some on heresay. Some of it is total bollox, scuse my French.......</font color=blue>

<hr width=100% size=1><font color=blue>A convert to steel boats and displacement cruising - the only way to go</font color=blue>

 

[Dave_Seager]

I have been looking for a twin-engined boat over the winter and have got to the point of trial runs with two of them. The first subsequently failed its survey and the second one is still proceeding. In both cases, there was a difference of about 1,000 r.p.m. indicated by the tachometers at full throttle. My problem is that, having little experience of twin engines, I am not sure what to expect.

In the case of the boat we are currently considering, the readings were about 2,500 and 3,500 r.p.m; about 20% difference. I am now inclined to think that the low tachometer reading may be incorrect as I did not need to apply any noticable correction to the helm to keep the boat straight at speed. It appears that the alternator on that engine cannot be clamped securely, so there is a good chance that the belt is slipping. Am I right in thinking that AQD31As run the tachometer on a signal from their alternators?

Thanks to everyone for their contributions to this thread. My apologies for the delay in responding, but I have been having PC problems this week.

<hr width=100% size=1>Dave Seager
Weybridge UK

 

[hlb]

Ive never seen a tachometer read right yet.

<hr width=100% size=1> <font color=blue>No one can force me to come here.<font color=red> I'm a volunteer!!.<font color=blue>

Haydn

 

[miket]

Can't answer your last question I'm afraid.
Disparity of 1,000rpm is somewhat excessive!

Just be aware that if you have to replace the tacho's they can be expensive.
I had 2 new ones for my TAMD61A's which came in at £300 the pair! (after a good discount!!)

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[allafloat]

i bought a boat that had sunk in the thames, it was fully submerged for three days and full of silt by the time we recovered it. The engines were volvo aqd32a,s on 270 sterndrives. After cleaning the fuel tank and refilling with new derv, taking out the injectors cleaning and replacing a new battery was all that was needed to get the engines running again apart from drying out the electrics. I afterwards wanted to strip the engines to see the internal condition and all was as well as could be expected for 30 year old engines. It cost me 600 quid for new gaskets and seals that i did not really need. the parts for these are available at a good price from COASTAL RIDES numbers in all the boat mags lots more to say but have to go, good luck