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Weird L96 engine start up issue


BarefootFool

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Last season I got a used 2011 Response with an L96 engine and only 102 hours. The boat is truly spotless. When I start it for the first time when cold and let it idle the temperature will always overshoot badly up to 230 degrees or so.

I addition, it will sometimes make a knocking sound and the hoses jump around. I think it is making steam in the engine that is somehow exploding in the hoses. If I rev the engine up to about 1500 RPM during the warm up process the temperature slowly comes up to 160 and stays there.

It works just fine after that. I am assuming the water pump doesn't move enough water during the warm up at idle to get sufficient flow through the engine. After the thermostat opens the flow must increase because it never heats up. I have checked the pump and it is fine. Could there be a blockage somewhere or is this a design flaw. Anybody have a similar problem. I must operate the boat at idle for some distance to get from my dock to the ski zone. If I could have operated it faster I would never have noticed the problem. Any ideas?

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Indmar had a service announcement  to the cooling system on the L96, mid year production of 2012 if I remember 

corectly. I would give indmar a call, they'll defiantly help you out. Mine was already factory retrofitted at Indmar 

Edited by Dare2goBare
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The L96 has small hoses that are connected to small "air purge" tubes on each head and then go to the exhaust.  If these hoses or tubes get plugged up with debris, steam can get trapped in the cooling system at idle and cause an overheat.  Some models have the purge hose connected to the muffler, exhaust, or a transom thru hull (depending on model year).  Removing and blowing air through the tubes, or using a small stiff wire may clear any trapped debris.  2012 L96 and LS3 models with tubular exhaust have a t-stat housing and plumbing update.  Check with your dealer to see if your motor is included in this update.  There are other things that can cause overheating, but hopefully this will give you a good place to start.

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Thanks Mike and others who responded. The boat is presently stored away in the garage next door and it's cold here. I will check out all the leads you have given me when it warms slightly.

I wonder if there is a source of service bulletins available online or elsewhere. I can't find any with a simple Google search. The nearest Malibu dealer is about 40 miles away and I'm not very impressed with them.

 

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  • 2 weeks later...

@BarefootFool:  If I assume your impeller check was simply visual, just a suggestion, if you do not find an issue you might swap your impeller for a different or new one.  I have found impellers that for some reason, either do not prime themselves very well (and need an RPM burp) to achieve the prime or they simply don't push enough water to keep an engine supplied (which does not sound like your issue).  If you have another impeller laying around, check softness of each as a comparison.

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5 hours ago, Woodski said:

@BarefootFool:  If I assume your impeller check was simply visual, just a suggestion, if you do not find an issue you might swap your impeller for a different or new one.  I have found impellers that for some reason, either do not prime themselves very well (and need an RPM burp) to achieve the prime or they simply don't push enough water to keep an engine supplied (which does not sound like your issue).  If you have another impeller laying around, check softness of each as a comparison.

good idea

also, keep in mind, that the center, splined shaft can fail at the bond to the rubber.  can be hard to see.

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first, I recommend you stop letting your engine getting up to 230C...

Second, my boat reacts like that after draining the engine...  If I start the boat, and immediately get it moving through the water (even at idle) I don't have the problem.

- this isn't a problem in the summer because I never drain the engine.  I can start it and idle for a long time without temp going up.

- this is a pain in the butt in the winter because I can not warm up the boat (and heaters) before folks join me at the lift.

 

My boat has the additional drain out the transom.

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I decided to call Indmar and see if they had an answer. I didn't expect much, but I think I got the answer. Somebody named Tom (I think) who was very knowledgeable said it is characteristic of the 6.0 and 6.2 motors.

He told me you must "bump" the idle during warm up. He said the water pump can't supply enough water for this engine at idle. Seems to me this is a design defect, but he would not say so.

Many owners would not notice this problem if they start the boat and run it faster during warm up. I can't do that because I live in an idle zone so I have to start it and run it at fast idle before I go skiing.

Guess I got my answer. Thanks to all who replied.

 

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32 minutes ago, BarefootFool said:

I decided to call Indmar and see if they had an answer. I didn't expect much, but I think I got the answer. Somebody named Tom (I think) who was very knowledgeable said it is characteristic of the 6.0 and 6.2 motors.

He told me you must "bump" the idle during warm up. He said the water pump can't supply enough water for this engine at idle. Seems to me this is a design defect, but he would not say so.

Many owners would not notice this problem if they start the boat and run it faster during warm up. I can't do that because I live in an idle zone so I have to start it and run it at fast idle before I go skiing.

Guess I got my answer. Thanks to all who replied.

 

I have this issue as well, with the electronic throttle I can't bump the throttle unless it is in gear (forget crawling down to lock it out).  Was hoping you were going to have an answer...

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1 hour ago, BarefootFool said:

He said the water pump can't supply enough water for this engine at idle. Seems to me this is a design defect, but he would not say so.

Which water pump?  Raw water or engine water pump?  If raw, Johnson does make 2 sizes.  If yours isn't already the big one that might help.  If engine water pump, maybe a smaller pulley?

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4 minutes ago, ski40mph said:

I wish they would put a neutral button back into the system for just this reason.

They have. 2015 and up I believe. And some 14 models like the LSV and VTX. IIRC.

Edited by ahopkinsTXi
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46 minutes ago, BarefootFool said:

He was talking about the raw water pump. Do you know the model of the larger Johnson pump and where to get it?

This is probably the one you already have.

http://www.marineengineparts.com/johnson-pump-10-24915-01-raw-water-pump-larger-impeller-size-crankshaft-mounted.html

I would think that if it is really a problem for your particular situation (extended idle) that you could put an electric pump in parallel with the raw water pump and run it only when needed.

One of these may do well.  6 gpm should be enough extra flow.  Not sure if they are ignition protected but they look to be well sealed motors. 

https://www.amazon.com/PC1-Portable-Battery-Powered-Transfer-Attachment/dp/B000BQO5RM/

https://www.amazon.com/SEAFLO-Water-Diaphragm-Pressure-Pump/dp/B01CO5N38E/

Either should prevent back flow - which you would be bad.  Biggest problem will be installing "T" fittings in your lines.  Find them here: http://www.sprinklersupplystore.com/Poly-Tees-s/189.htm

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