yanmar 260 6cy overheat

[SwanseaBoat]

This has got me foxed;
Last week the overheat alarm sounded at 3200 rpm , soon after leaving harbour. Throttle back, cooled to to 90degrees. Throttle up and she overheated again. Back to base slowly.

So I viewed the MBM video, and spent an hour today looking for a cause.
Plenty coolant. Raw water filter clean. Plenty water pumped out of the exhaust. Impeller housing cold to touch. Ran her at 2000rpm warped to the pontoon for ten mins, seemed stable at 90 degrees. Throttle up to 2500rpm and the temp immediately started to climb over 100degrees.

So I think there is a problem, but I dont know what: slipping impeller drive belt? failed temp sensor(digital instruments)? Any thoughts Folks?

 

[volvopaul]

This has got me foxed;
Last week the overheat alarm sounded at 3200 rpm , soon after leaving harbour. Throttle back, cooled to to 90degrees. Throttle up and she overheated again. Back to base slowly.

So I viewed the MBM video, and spent an hour today looking for a cause.
Plenty coolant. Raw water filter clean. Plenty water pumped out of the exhaust. Impeller housing cold to touch. Ran her at 2000rpm warped to the pontoon for ten mins, seemed stable at 90 degrees. Throttle up to 2500rpm and the temp immediately started to climb over 100degrees.

So I think there is a problem, but I dont know what: slipping impeller drive belt? failed temp sensor(digital instruments)? Any thoughts Folks?

Sorry but you cannot possibly test your engine that way, take a minute to think about what you have done........

An engine is matched to its prop to perform at wot under its maximum rated load, by tying your boat to the pontoon your seriously overloading the engine, had it been a common rail Volvo you probably would not have got it to rev over 1000rpm as it would sense it's load relative and just sit there where its happy, but old mechanical governor can't see that so it just pumps more fuel in to the cylinders in the hope it balances the governor in relation to throttle position.



Obviously it can't so it overheats, sorry you have gained nothing by doing that other than maybe polishing your bores up with the extra fuel thrown at them and wearing the rings out.

I presume it's a 6 lp? , yanmar run there heat exchanger sizes on the limit, I'd guess your tube stack is partially blocked, also the inside which you cannot get at easily will be furred on the outside of the tube stack therefore it's not dissipating the heat from the internal coolant.

Remove the heat exchanger and soak it in rydelime solution then jet wash it inside and out as much as you can, and use pink coolant as it seems not to cavitate as much as green which has been tested by the yanmar factory.

You can only test properly under load out on the water, that's how it's been designed to perform.

I trust your hulls fairly clean and the prop is the correct diameter and pitch.

 

[DAKA]

Agreeing with volvopaul, but in the interests of completeness it is possible if you really think the symptoms are like a belt slipping for the impeller to slip on the hub.

Holding the impeller in a vice doesnt help as the vice clamps the impeller to the hub.

large Screw driver wedged in the impeller then screw driver held in the vice , wet the impeller which now may spin on the hub and produce the symptoms you describe but its very rare and highly unlikely.

How old was the impeller , who fitted it (did you watch) and where was the impeller sourced ?

 

[SwanseaBoat]

Thank you for your comments. Busy week at the coalface, so I'll keep it short.
Newish Yanmar 6cy 2010 fit, 290 hrs. I have owned her the last 25.
Serviced at 250hrs.
Bum clean.
Pink coolant.
The engine may even be under warranty still, will check.
In light of your thoughts, I have asked for a professional to take a look.
Will let you know, Cheers

 

[Latestarter1]

Thank you for your comments. Busy week at the coalface, so I'll keep it short.
Newish Yanmar 6cy 2010 fit, 290 hrs. I have owned her the last 25.
Serviced at 250hrs.
Bum clean.
Pink coolant.
The engine may even be under warranty still, will check.
In light of your thoughts, I have asked for a professional to take a look.
Will let you know, Cheers

Because you made no mention of Yanmar model VP assumed you had a Toyota based LP, however turns out you have a BMW base BY2 (Not CY). Not a great deal of experience of BY here Cookee exepted

Keep us posted as to professional diagnosis we are all ears.

Your Yanmar warranty is 24 months from the date of delivery to the first customer.

 

[SwanseaBoat]

So, Engineer says the raw water pump not pumping adequte water at revs.
Impeller worn but apparently intact. Also thermostat not present???
Engineer has replaced both and runs ok. Awaiting run out at speed.

Could the old impeller have been slipping at high revs on its drive shaft?
I know the previous owner, who ran this Yanmar BY 6Cy for 260 hrs no probs.

Update after seatrail. Weather, tides and work to juggle. Cheers.

 

[Latestarter1]

So, Engineer says the raw water pump not pumping adequte water at revs.
Impeller worn but apparently intact. Also thermostat not present???
Engineer has replaced both and runs ok. Awaiting run out at speed.

Could the old impeller have been slipping at high revs on its drive shaft?
I know the previous owner, who ran this Yanmar BY 6Cy for 260 hrs no probs.

Update after seatrail. Weather, tides and work to juggle. Cheers.

Thank you for keeping us updated.

Not sure where you dug this tech up from, however sounds like a typical product of Barrus training.......

'Water pump not pumping adquately at high reves'. As far as I am aware there is no test point on the Yanmar BY to take a pressure measurement therefore must be pure conjecture.

'Thermostat not presesnt' eloquent way of saying thermostat is missing! What the heck!

Thermostat MUST have been in there at some point, and taking this vital comonent out of a modern engine WILL cause overheating even when fully open stat block/head flow still requires small Delta 'P' offered by the stat to circulate the coolant properly.

Two components changed, but no sea trial????????? Process should have been change impeller, sea trail, then sort out thermostat issue and sea trial again.

However as we seem to live in a world of numpty inadequately trained, brainless techs we have to live with what we have got. The BIG question is why the stat was removed in the first place? What were temperatures when you sea trialled the vessel prior to purchase? I would be extremely concerned about the fact that stat has been removed in the past........

As to the raw water pump forget it, the BMW marinisation was done in Austria and I would suspect they used a Johnson pump or similar, all decent stuff. Impeller is positively driven either by Woodruff key or splined hub.

Good luck.

 

[Jim@sea]

I had an impeller where the glue holding the rubber to the brass spline has become brittle and became unstuck. At high revs the centre spun but the rubber impeller blades did not. although at tick over it worked.
While you are checking for the fault you may as well fit a new impeller anyway
PS It was an Iveco Impeller not a Yanmar Impeller.

 

[NorthUp]

You have a Yanmar..
similar engine to the Yamaha 240 STI?
After about 5 years old, depending on use obviously, a problem shows on the yamaha, with the exact same symptoms you describe.
The problem may be corrosion in the turbo exhaust elbow/ water injection point, restricting the flow of cooling water through the system.
If you have a twin engine setup, and one engine is ok, compare the pressure in the seawater hoses after the waterpump, by squeezing with fingers.

The cure on Yamahas is new elbows, fabricated in stainless steel- the Yamaha cast iron version is silly money.

Hope this is of help, its another possibility anyway.

 

[Latestarter1]

You have a Yanmar..
similar engine to the Yamaha 240 STI?
After about 5 years old, depending on use obviously, a problem shows on the yamaha, with the exact same symptoms you describe.
The problem may be corrosion in the turbo exhaust elbow/ water injection point, restricting the flow of cooling water through the system.
If you have a twin engine setup, and one engine is ok, compare the pressure in the seawater hoses after the waterpump, by squeezing with fingers.

The cure on Yamahas is new elbows, fabricated in stainless steel- the Yamaha cast iron version is silly money.

Hope this is of help, its another possibility anyway.

NorthUp,

Your comments are not in the least helpful. This thread got off on the wrong track because OP did not post his corrct engine spec, back on track now all you have done is muddy the water again.

I have NO CLUE what a Yamaha 240 STI is.......Yamaha did produce a marinisation of the Toyota block similar to Yanmar and it was called the Yamaha ME422. However early on we were given the heads up that this was a Yanmar BY2, nothing whatsoever to do with Toyota, a little BMW boutique diesel motor with its roots firmly established in Europe, it was even marinised in Austria not Japan.

Bad enough for OP with Two Gun Tex the tec shooting from the hip and replacing two components at the same time without being led completely up the garden path!

 

[NorthUp]

Latestarter
apologies for my typing error, I transposed the 4 and 2 when describing the ME420STi.
Google images , by coincidence the first image on my confuser:

http://www.google.co.uk/search?q=ya...7D-GM0AWajoGIDw&ved=0CD0QsAQ&biw=1132&bih=666

describes the very part I encountered a while back, the failure of which results in identical symptoms to the OP's engine.

Lets hope the OP finds a cure and posts it, and we can all learn a bit more.

 

[SwanseaBoat]

No luck yet, no surprise to any of you.
Beautiful this morning in Swansea.
Yanmar BY 260 overheated at 2000 rpm and alarmed before we got out of the river. Steamy exhaust.
Back in on tickover, and she cooled down.
So it seems to me that the raw water pumps, but not enough.
Must be restriction somewhere in the circuit...advice on where to look next?
e.g. seawater intake hull fitting-can something jam in there? That would take a lift or an endoscope.
e.g. calcification in hose or heat exchanger, but this engine is 290 hrs from new in 2 years.
Or as suggested, restriction in the exhaust mixer.
Apologies for non-tech decription. I do ops for the nhs normally.
And the engineer's gone festive for a week now.
So the next installment will be along in a while.
Cheers

 

[solitaire11]

pump..

this happened to my neighbours volvo ad this year, overheated at river speeds and fine on tick over, we stripped and checked everything , even swapped loadsa bits off the other engine. turned out to be the raw water pump was worn!!! could'nt believe it! never heard of that before.. refurbish kit fitted and runs sweet as a nut now, done both now and they run cooler at planing speeds now, gotta be worth a try.

 

[Latestarter1]

No luck yet, no surprise to any of you.
Beautiful this morning in Swansea.
Yanmar BY 260 overheated at 2000 rpm and alarmed before we got out of the river. Steamy exhaust.
Back in on tickover, and she cooled down.
So it seems to me that the raw water pumps, but not enough.
Must be restriction somewhere in the circuit...advice on where to look next?
e.g. seawater intake hull fitting-can something jam in there? That would take a lift or an endoscope.
e.g. calcification in hose or heat exchanger, but this engine is 290 hrs from new in 2 years.
Or as suggested, restriction in the exhaust mixer.
Apologies for non-tech decription. I do ops for the nhs normally.
And the engineer's gone festive for a week now.
So the next installment will be along in a while.
Cheers

Can we back up a bit and have some history. Or perhaps I can ask some questions.

#1 When you purchased vessel you performed sea trials, and can we assume motor made WOT of 4,000 rpm with stable temperatures?

#2 If yes to 1 can you describe operational hours up to the point overheat occured?

#3 I have the BY1 training package but not BY2 when they swapped dry exhaust manifold for wet set up. The BY1 water pump did not have any test ports which we criticised, may be worth checking to see if they took any notice of us, you will be looking at a MAXIMUM of 15 psi on water pump outlet if it has a test point. Adding a water cooled manifold to the design must have increased heat rejection to coolant which required a larger capacity heat exchanger and charge cooler.

#4 If you have no test point on water pump outlet and we have to assume tech checked out the raw water pump and drive properly when he fitted new impeller nothing for it but to go through the raw water side step by step, starting with the heat exchanger.

#5 Before committing to 4 has your tech actually been on the BY training course at Barrus?

I have real concerns regarding the missing thermostat it makes me suspicious, may be a wise move before you go any further to make a request for the engine warranty history.

If you require BY1 technical package just PM me.

 

[Latestarter1]

Swanseaboat,

I dug out the BY1 technical package ready for your shout. Confirmed that raw water pump is Johnson and did not change BY1 to BY2 so you have no pressure tappings.

Following on from my comment regarding your tech and having been on the Yanmar BY training I discovered something reading the tech package, engine overtemp looks like it triggers torque curve de-rate.

When Magna did the marinisation their first cut was to use Bosch KTS tool which caused guys in the U.S to go beserk with every Yanmar electronic engine platform requiring dealer to purchase a separate and expensive diagnostic tool, BMW BY, Toyota LV and Yanmar LY3. Magna came up with very simple solution of using cheap as chips after market OBD2 code reader which has 9 pin Deutch connector instead of OBD plug.

If your tech is a Yanmar guy he should know all and be able to see exactly what is going on, as well as being able to check out possibility of uncleared hi-temp de-rates which occurred prior to your purchase of vessel. I know it is good repair practice for tech to clear inactive fault codes after problem is fixed, however does not always happen............

 

[SwanseaBoat]

Mystery solved: Liftout today revealed plastic bag wedged up intake grill.
Explains all the symptoms.
I have got a photo, but I cannot seem to paste it.
Thanks all for your thoughts,
seatrial tomorrow...

 

[Latestarter1]

Congratulations!

 

[rafiki_]

Congratulations!

+1

 

[longjohnsilver]

Often the most simple of solutions. Just a pain it got there in the first place.