Engine Height?

totallydave · 18 November 2019, 18:36

Hi, I expect this subject comes up time and time again, but each situation is slightly individual so...

I am not getting blow-outs or any issues with turning, speed etc. The only issue I have had is the engine over heating and the theory (from the local dealer) is that it might be getting pockets of air.

As you can see from the photo. The bottom of the cavitation plate is about 1cm higher than the bottom of the hull, when trimmed parallel. Sorry you can't see the water inlet in the photo as it is behind the straight edge but is is probably about an inch down from the top of the straight edge.

I also have a video looking down at the cavitation plate whilst planing. Haven't worked out how to load that yet but the plate is just below the surface.

So what's the opinion on height from you guys?

whiskylee · 18 November 2019, 21:26

Looks textbook engine height, the cav plate is in line with the bottom of the hull.
I run my cav plate 3 -4 inches above bottom of hull on my race boat with standard water pick up lower unit & manual water pressure gauge.

I assume it's a honda engine, do you have digital gauges with temp & water psi etc, when are you seeing an overheat warning at idle or planning speeds.

Again I assume you have a healthy water pump impeller etc

Ribtecer · 18 November 2019, 21:46

Quote:

Originally Posted by whiskylee

Looks textbook engine height, the cav plate is in line with the bottom of the hull.
I run my cav plate 3 -4 inches above bottom of hull on my race boat with standard water pick up lower unit & manual water pressure gauge.

I assume it's a honda engine, do you have digital gauges with temp & water psi etc, when are you seeing an overheat warning at idle or planning speeds.

Again I assume you have a healthy water pump impeller etc

Interesting thread, thanks guys this means my 90 hp Yamaha is about right on the transom of my Ribtec.

Now if I only had a replacement cowling I'd be as happy in a pig in ship!!!

Many thanks again.

totallydave · 18 November 2019, 22:50

Quote:

Originally Posted by whiskylee

Looks textbook engine height, the cav plate is in line with the bottom of the hull.
I run my cav plate 3 -4 inches above bottom of hull on my race boat with standard water pick up lower unit & manual water pressure gauge.

I assume it's a honda engine, do you have digital gauges with temp & water psi etc, when are you seeing an overheat warning at idle or planning speeds.

Again I assume you have a healthy water pump impeller etc

Yes 2016 Honda 225 with digital gauges. Temperature was getting to about 93-95 then the engine cutting out. Dealer tells me pumps, impeller and thermostat are OK and that the gauges only read one of the 2 temps from the engine. Believed that the other temp is what is causing the cut out and that it may be driven by steam which is created by 'gulping' air every once in a while. Hence the post about height, in case that was a factor.

jonp · 19 November 2019, 02:59

Depends on the intended use.

totallydave · 19 November 2019, 08:40

Quote:

Originally Posted by jonp

Depends on the intended use.

So given a family RIB for touring, blasting and water skiing, it would suggest I'm about right at 10mm above.

whiskylee · 19 November 2019, 08:58

Quote:

Originally Posted by totallydave

So given a family RIB for touring, blasting and water skiing, it would suggest I'm about right at 10mm above.

Yes looks at the right height

gtflash · 19 November 2019, 09:27

My prop shaft runs level with hull, cav plate several inches above. I do have some setback and step hull but no cooking issues. Yours looks pretty damn standard setup.

On evinrude forums there are multiple over heats. Often a poorly fitted impeller or blocked cooling system etc. It must be similar for hondas.

Is it a long standing problem or new?

whiskylee · 19 November 2019, 09:32

Just googled honda outboard mounting height and there is a honda ops manuals and yours is mounted as per manual [emoji106]

charliee · 19 November 2019, 09:33

Is this a new issue or is this a new package. The engine looks to be perfectly slung but can you drop it down and test without re drilling?

Last Tango · 19 November 2019, 09:43

"Overheating" issue with my Honda was a faulty temperature sensor....

Locozodiac · 19 November 2019, 12:49

Some issues :

Is it a clamp or bolt on motor ?
Is it an electric or manual trim motor ?

Can you post another pic of said motor shot sideways without the level ruler to have a look, there's a short cut version that will let you know instantly if that nice motor sits and runs at the sweet transom height which is not mentioned nowhere and was dialed by pure water experimentation.

Happy Boating

Waterman · 19 November 2019, 13:15

Quote:

Originally Posted by jonp

Depends on the intended use.

Very Useful guide. [emoji1303]

Last Tango · 19 November 2019, 13:52

There is absolutely nothing "wrong" enough with the engine height that would cause it to overheat.......Look elsewhere for the problem...

Pikey Dave · 19 November 2019, 18:10

Sounds like dealer bollix to me. How far can you trim the engine up from “normal” before it lets go?

totallydave · 19 November 2019, 21:03

Quote:

Originally Posted by charliee

Is this a new issue or is this a new package. The engine looks to be perfectly slung but can you drop it down and test without re drilling?

To be honest I don't know if it has been a long running issue as I only bought the boat late last year and (due to skiing accident) did not use it until summer this year.

Dealer has had it several times and checked all obvious things. I've now switched to a larger prop which brings the revs down a little.

One test since doing that and (at full chat) engine temp does get up to 103C but it did not cut out. Will have to just keep testing.

Pikey Dave · 19 November 2019, 21:33

Quote:

Originally Posted by totallydave

To be honest I don't know if it has been a long running issue as I only bought the boat late last year and (due to skiing accident) did not use it until summer this year.

Dealer has had it several times and checked all obvious things. I've now switched to a larger prop which brings the revs down a little.

One test since doing that and (at full chat) engine temp does get up to 103C but it did not cut out. Will have to just keep testing.

Paradoxically a larger prop could make it worse. The engine has to work harder to spin the prop. I was going to ask what your WOT was/is.
I’d be tempted to remove the thermostat(s) & see if the problem persists.

Covey · 20 November 2019, 12:55

Had this problem with a 225 Honda a few years ago, second stat was opening but not fully, causing the problem, as said pop out your thermostats both of them and if that doesn’t work, it’s going to be a faulty sensor, common enough on Hondas

Locozodiac · 20 November 2019, 17:34

Any given right height dialed on a dry installation is relative as you won't know at which lower leg is water flow passing at speed, ideal is to skim right under the upper small plate which will assure excellent lower leg water height and proper cooling if happens to be a motor height issue.

To check that need a visual inpsection on what's going on at back middle transom, run combo at speed on flat calm water while motor is trimmed to neutral, pull head out and check, raise or lower the motor till that cond is fully met.

Happy Boating

totallydave · 20 November 2019, 19:23

Quote:

Originally Posted by Covey

Had this problem with a 225 Honda a few years ago, second stat was opening but not fully, causing the problem, as said pop out your thermostats both of them and if that doesn’t work, it’s going to be a faulty sensor, common enough on Hondas

That's interesting and sounds very relevant.

Dealer has had both thermostats out, tested them and put them back which did not fix the issue.

I'm switching dealer now for several reasons, so if it happens again I will send the new guys down this track.