Engine high temp alarm

[Donnie macinnes]

I own a Redbay stormforce 6.1 powered by a mercury D1.7DTI alpha diesel. The engine runs well, but when I open her up to 30knts I get a high temp alarm after about 5 mins, pulling her back for about five mins cancels the alarm. She runs for hours at 25 Knts with no alarms. During the winter layup the heat exchanger was cleaned and the impeller changed which I thought may have been the cause. I have also just changed the electronic sensor but the high temp alarm still comes up when she is pushed hard. My next tact is to take out an electronic temp gun and measure what the actual temperature increase is when the alarm sounds.
Has anyone else experienced this problem with a Mercury engine and an Alpha A outdrive??

[willk]

Do you keep her afloat or trailered? Wondering if there could be marine growth inside the water intake passages?

Tell me, what's the deal for RIBs visiting Tiree this week - any moorings out or is there a place to tie up somewhere?

[beamishken]

It's a fairly common problem on those engines when you say cooler was cleaned was the core removed and cleaned with acid? And was the intercooler removed and cleaned at the same time? Either can become blocked and restrict flow
Is the turbo waste gate free to operate as those stick and means the waste gate doesn't operate so engine runs on full boost instead of dumping any excess pressure which can cause extra heat

[Donnie macinnes]

just launch her from trailer, the old harbour is fine for a rib, if the weather is ok the outside of the pier would be safe enough and with small tides you would probably remain afloat most of the time. The ferry pier in Gott bay is also ok in good weather conditions, unfortunately there are no moorings.

[Donnie macinnes]

Originally Posted by beamishken

It's a fairly common problem on those engines when you say cooler was cleaned was the core removed and cleaned with acid? And was the intercooler removed and cleaned at the same time? Either can become blocked and restrict flow
Is the turbo waste gate free to operate as those stick and means the waste gate doesn't operate so engine runs on full boost instead of dumping any excess pressure which can cause extra heat

Thanks will pass this onto the engineer who carried out the work on the engine.

[jwalker]

Not so common but another possibility is the engine being over fuelled, either by too much output from the injection pump or a faulty turbo supplying too little air. Over fuelling causes lots of heat.

[pilotwillie]

Originally Posted by Donnie macinnes

The engine runs well, but when I open her up to 30knts I get a high temp alarm

Amigo, big hello first of all !!!
I could also give you some advice (with regards the above quote) but it's not technical and therefore probably not what you want to hear ! 😃
I'm sure the knowledgeable mass on here can help you out before I come up for a meet. If not, then happy to ease back to 25kts for a cruise ! 😂
Hope you get a fix soonest.
Cheers,
Willie

[Donnie macinnes]

Hi Willie
Thought we had fixed the problem, but gave her a run to Coll last week and the alarm was still going off. More than happy to cruise at 25knts but would be nice to push her up to 30knts plus, especially in fine weather conditions. Did a day on the river for Derek yesterday, guess he was at the football bet he wishes he had just gone to work!!
Speak soon
D

[Donnie macinnes]

Thanks JW will pass that onto the guy that does the servicing of the engine. The boat was built in 2003 and has only done 500hrs, so its probably not been used enough over the years. The guy i bought her from told me about the problem but he put it down to the engine not getting enough water in, at high speeds. The problem never held him back he covered most of the West Coast including a trip to St Kilda.. I would just like to get to the bottom of it before heading to far from Tiree.

[beamishken]

It's not about the speed that you need to get it fixed for realy.Id be more concerned about how it would perform if it got rough and I needed to start working the engine harder to cope with the conditions that's not the time to be worrying about an overheating engine

[Donnie macinnes]

The sea conditions don't appear to make any difference to the alarm, I've been out in various sea conditions and all is ok, its just when you give her that extra few revs that the alarm sounds. But it would be good to get to the root cause. Thanks

[Erin]

Presumably the impeller casing has been checked for wear. I would be tempted to try a back flush on the block just in case there's debris stuck somewhere.