# Need the Brain Trust



## commtrd (Aug 1, 2015)

That does not sound like the compression plate. That sounds like the motor is too high for the tunnel to keep enough water on the lower pickups. Stated that the motor was lifted up by 3" so there is your answer. Sure Mac will be on here shortly to comment. He runs a HPX-T so can comment more accurately. Could post up a picture of the stern straight on with the motor lifted up all the way on the JP to see the bullet in relation to the tunnel. And compare the water pickups to tunnel etc.


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## firecat1981 (Nov 27, 2007)

Do you have a low water pickup on the motor? I doubt it's the plate. You raised the motor 3", that's significant.


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## Smackdaddy53 (Dec 31, 2012)

I have the same plate, prop, hull and motor and jacked all the way up it will overheat if the water is warm. Won’t do it in cooler months. It’s nothing more than the pickups are ingesting some air.
I am installing a Bob’s nosecone on my lower unit when I get time. There’s nothing wrong with your setup, the powerhead just needs more water. If my prop was losing grip and blowing out in turns I’d lower my jackplate and leave stock pickups but that’s not the case. I can run 33mph with the prop above the bottom of the hull so pickups it is. A cheaper option is a transom mount Bob’s with the hose etc but you need to run in nothing but clean water or it will suck up trash. I had one on my last boat and installed an inline raw water filter and it would clog with grass after running skinny in floating grass after about 100 yards. Nosecones are the way to go.


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## commtrd (Aug 1, 2015)

This Mac's boat and clearly has the bullet completely above the top of the tunnel. So evidently the tunnel can move enough water to keep it running cool.


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## Bruce J (Mar 4, 2018)

Thanks for the quick responses. I’m going to test it some more next weekend when I have my sons with me. But I’m surprised it lost pressure completely at about 4 on the jack plate since I assume that’s about where it would have been at 6 before I had raised the mounting position. And I assumed the plate would even help a bit. Oh well, I guess not. 

Will report back again when I can test it better. Thanks again!


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## Bruce J (Mar 4, 2018)

Let’s see if this works as I haven’t tried to post pictures yet. This one should be the fully raised position, jackplate at 6.


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## Bruce J (Mar 4, 2018)

Yeah, that didn’t look like it worked. Trying again...


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## Bruce J (Mar 4, 2018)

And here it is at 3 in the JP, which is equivalent to about 6 before I had raised the motor...


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## Bruce J (Mar 4, 2018)

Bruce J said:


> Yeah, that didn’t look like it worked. Trying again...


This one was at 6 on the jack plate, but I wasn’t running it that high.


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## Smackdaddy53 (Dec 31, 2012)

There’s no reason for your motor to get hot that low...my motor with JP sll the way down is as high as yours all the way up. You might need to look at your water pump and powerhead for corrosion and impeller/pump housing or pickup tube issues. 
I thought you had a 2 stroke like mine as well. Still shouldn’t be getting hot that low and I’d be looking for issues with your cooling system before changing anything else with the prop, plate or motor height.


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## Bruce J (Mar 4, 2018)

I hear you, but also wasn’t having any heat alarm issues other than occasionally from grass before these changes. But, it would always be good to get other issues checked out thoroughly. I had thought about getting the nose cone pickup also, but mainly because of the grass. My motor (and my 2-stroke before this one) seem to have an unusual attraction to it.


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## Smackdaddy53 (Dec 31, 2012)

Bruce J said:


> I hear you, but also wasn’t having any heat alarm issues other than occasionally from grass before these changes. But, it would always be good to get other issues checked out thoroughly. I had thought about getting the nose cone pickup also, but mainly because of the grass. My motor (and my 2-stroke before this one) seem to have an unusual attraction to it.


I have never seen or heard of a compression plate causing overheating. It doesn’t make sense, and plate should be better than no plate at all. I have not seen a Shaw Wing like yours cause issues either. Maybe you should take it off and run it or replace it with a Tran plate. I had one on my last boat, one on my current boat and lots of guys I fish with run them with no issues. I’m sure someone else will chime in.


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## Bruce J (Mar 4, 2018)

Mine’s a NewWater plate, but I agree that I doubt the plate is causing it.


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## Smackdaddy53 (Dec 31, 2012)

I started having issues with overheating with a motor I bought that came with the boat and popped the head covers off and was freaked out by how much salt and crud was built up in it. It’s worth a shot and gaskets are not expensive. I have also seen the water pickup tube not lining up or sealing with the lower unit water pump housing. Has the lower unit been dropped recently? That would be a big clue.


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## Bruce J (Mar 4, 2018)

Smackdaddy53 said:


> I started having issues with overheating with a motor I bought that came with the boat and popped the head covers off and was freaked out by how much salt and crud was built up in it. It’s worth a shot and gaskets are not expensive. I have also seen the water pickup tube not lining up or sealing with the lower unit water pump housing. Has the lower unit been dropped recently? That would be a big clue.


The impeller was changed about 15 months ago, but I don’t think they checked the head or intake tubes, but that’s a really good idea in any case.


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## sjrobin (Jul 13, 2015)

Bruce J said:


> The impeller was changed about 15 months ago, but I don’t think they checked the head or intake tubes, but that’s a really good idea in any case.


The less water flow and more aerated water to the cylinder head the hotter the engine temps and more hard salt deposits. The head temps can run just under alarm but run progressively hotter with more engine hours. But in this case your F70 looks low hours. The comp plate is not causing high temps, just lack of water to intake.


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## Bruce J (Mar 4, 2018)

I'm taking her in for a check-up after Memorial Day weekend. I think I'll get a Bob's nose cone pick-up too as it should be a lot more resistant to getting blocked from grass. I don't know if you guys get shut down as much as I seem to for that, but I mainly fish on our around Estes Flats and the grass is always an issue.


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## Smackdaddy53 (Dec 31, 2012)

Bruce J said:


> I'm taking her in for a check-up after Memorial Day weekend. I think I'll get a Bob's nose cone pick-up too as it should be a lot more resistant to getting blocked from grass. I don't know if you guys get shut down as much as I seem to for that, but I mainly fish on our around Estes Flats and the grass is always an issue.


There wouldn’t be as much floating grass if the tourists would stop running their deep vees aground then blow a roostertail of mud, sand and grass out and burn up the water pump before they call the airboat to jerk them off (the grass flat). Estes Flats used to be great and now it’s like a magnet for googans.


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## Bruce J (Mar 4, 2018)

Yeah, there's definitely some of that. I didn't fish it in "the good old days", so I don't have a comparison. I don't seem to have as much problem while running on the flat as when in the intercoastal. When running from my house down to Cove Harbor (about two miles) I'll get shut down about half the time. Pretty annoying.


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## Smackdaddy53 (Dec 31, 2012)

Have you discussed this with Jack? He could help you more than anyone abd I bet if you drag your boat to his shop he could figure it out pretty quickly. I’d do that before anything.


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## Bruce J (Mar 4, 2018)

When I got my prop from him about a month ago, I asked him if he would do the rigging (prop, wing, and motor raising) and he wasn't really keen on doing that. So I did all of that myself per his recommendations on each, and they're pretty simple things that I don't think could have been done any other way. We never discussed a nose cone/low water pick-up, though.


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## Smackdaddy53 (Dec 31, 2012)

Bruce J said:


> When I got my prop from him about a month ago, I asked him if he would do the rigging (prop, wing, and motor raising) and he wasn't really keen on doing that. So I did all of that myself per his recommendations on each, and they're pretty simple things that I don't think could have been done any other way. We never discussed a nose cone/low water pick-up, though.


I’m just asking because something doesn’t seem right like you have a salt, corrision, water pump, thermostat or pickup tube issue. Have you cleaned out your thermostat?


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## Bruce J (Mar 4, 2018)

The impeller is relatively new, but I don't think the other things have been checked/changed. But Jack wouldn't help with any motor work like that, would he? I would otherwise take it to Chris's or some other Rockport shop.

Also just thinking about it, the water pressure and temp were fine when I dropped the motor a bit, so I would assume the thermostat is working. It was interesting watching the water pressure gauge as it just dropped from 20+ to essentially zero once I was fully up on plane for a few seconds. It certainly seems primarily like insufficient water ingestion at full speed and above average elevation. I'm going to have the issues you mentioned checked out anyway, just as good measure.


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## trucha del mar (Apr 1, 2016)

Bruce - We don't have a compression plate on our HPXT/Yammie T60, but a while back we raised our motor up a skosh and concurrently removed the water intake screens and filled the top half of them with marine silicone. I spoke with Charlie at Kroll's Marine and he recommended doing this to decrease the amount of aerated water coming into the intake, i.e. keeping the only intake opening lower in the water. Full disclosure: we never experienced a problem before trying the silicone trick, so it might not have actually solved anything, but I've never had a high temp warning after doing this. Certainly a very easy thing to try.


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## Bruce J (Mar 4, 2018)

trucha del mar said:


> Bruce - We don't have a compression plate on our HPXT/Yammie T60, but a while back we raised our motor up a skosh and concurrently removed the water intake screens and filled the top half of them with marine silicone. I spoke with Charlie at Kroll's Marine and he recommended doing this to decrease the amount of aerated water coming into the intake, i.e. keeping the only intake opening lower in the water. Full disclosure: we never experienced a problem before trying the silicone trick, so it might not have actually solved anything, but I've never had a high temp warning after doing this. Certainly a very easy thing to try.


That’s an interesting point. There is what appears to be a water intake grate above the anti-cavitation plate, but I couldn’t find it identified that way in the manual or anywhere else. But if that’s what that is, I can see how the compression plate would keep any water from getting to this upper intake. That would explain why the temp got worse after I put on the plate, particularly at the higher elevation. It would also explain why it got better when I dropped the jack plate to a level which perhaps allowed water to over the top of the new compression plate. 

But this also raises a few more questions. First, I would think this would be a problem for everyone running a compression plate, so why aren’t a lot more people having this problem? Second, can the lower/main intake take in enough water on its own if the upper one is blocked? Third, has anyone else done this?


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## Surffshr (Dec 28, 2017)

There isn’t an upper intake. IDK exactly what the grate is above your compression plate, but it isn’t an intake. First I’ve ever heard of blocking off part of an intake, and I prolly wouldn’t do that myself.


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## trucha del mar (Apr 1, 2016)

Surffshr said:


> There isn’t an upper intake. IDK exactly what the grate is above your compression plate, but it isn’t an intake. First I’ve ever heard of blocking off part of an intake, and I prolly wouldn’t do that myself.


Correct, the only water intake is below the cavitation / compression plate. But again, we've been running the motor with the top half of the intake grate blocked off for about 1.5 years with no apparent negative impact on water pressure or engine temperature.


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## Bruce J (Mar 4, 2018)

Okay, thanks. The grate I was talking about is immediately above the plate and at the back/tailing edge of the motor. It isn’t identified in the manual. Exhaust maybe?


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## Guest (May 22, 2018)

water outlet. If you run until t stats open on a hose you will see water coming out of those “grates” Some act as exhaust relief also.


Bruce J said:


> Okay, thanks. The grate I was talking about is immediately above the plate and at the back/tailing edge of the motor. It isn’t identified in the manual. Exhaust maybe?


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## No Bait / Lures Only (Apr 10, 2011)

trucha del mar said:


> Bruce - We don't have a compression plate on our HPXT/Yammie T60, but a while back we raised our motor up a skosh and concurrently removed the water intake screens and filled the top half of them with marine silicone. I spoke with Charlie at Kroll's Marine and he recommended doing this to decrease the amount of aerated water coming into the intake, i.e. keeping the only intake opening lower in the water. Full disclosure: we never experienced a problem before trying the silicone trick, so it might not have actually solved anything, but I've never had a high temp warning after doing this. Certainly a very easy thing to try.


I did this to the top holes on my intake screens of my 2 stroke 90 Yamaha an it solved lots of issues


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## Bruce J (Mar 4, 2018)

I managed to track down Jack Foreman on the phone yesterday. He felt that everything was probably working just fine as I described it, and didn't think it was unusual that I ran out of of water pressure at the higher/highest jack plate elevation since I had also raised the motor mounting position. It would just take some practice to find the sweet spot of elevation, trim, etc where the boat will run best and at proper water pressure.

He said the extra elevation is still useful for jumping up in 3 inches less water than before, but I'll just need to drop the jack plate back down a bit after getting up on plane to keep from losing the water pressure. I like that extra flexibility.

Finally, we talked a bit about nose cone pick ups. He didn't have a lot of experience with them, but thought it would be fine to add one. He did caution to get one with the holes not on the very bottom of the cone since those can be more prone to getting clogged up by mud.


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