Could these little salt dams (pics) in the head really cause weak, hot telltale?

[pcrussell50]

So when I dropped a new (to me) 2.4/200 powerhead onto a known good mid/lower, I got a weak, hot telltale. No overheat buzzer though, and I tested it. Compression and leak down are both good because I tested those before I removed the heads.

When I removed the heads, I found these salt dams outside the sides of the chambers:
link: https://postimg.cc/cKBy6c9n

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https://postimg.cc/cKBy6c9n
https://postimg.cc/cKBy6c9n

Looking for a sanity check: I cleared away the salt dams, but before I put the heads back on, it occurs to me to wonder if those little salt dams could really be cause of a weak, hot telltale? Again, with NO overheat buzzer.

Somehow my visualization of the flow situation is brain farting and I'm not seeing something right.

-Peter

[rock]

Can't imagine it would but clearing them out has to help.

Rock

[pcrussell50]

Can't imagine it would but clearing them out has to help.

Rock

That leaves me at a loss as to the low flowing weak and hot telltale, without overheat buzzer.

Maybe it's time to pull the water pump, but it was raging good last year and hasn't been used since.

-Peter

[rock]

Impellers usually fail first time out cuz the vanes have taken a set over winter. Other way to explain is one vane is bent almost 90 degrees and has sat that way over the winter and sometimes they either break off or just don't reach the cup wall therefore cavitating.

Rock

[sonicss33]

On this you are being way too analytical, replace the water pump and accept the win. BTDT. :smiletest:

[25two.stroke]

How hot is hot? They pee hot with thermostats. They pee 143 deg. That's hot to the touch. Same with the heads. What is the temp number as read with a laser thermometer?

[skialot2]

Telltale hoses are connected to the thermostat housings. The water should come out hot. Just not burning hot. My 1992 135 has a weak telltale also. But it has 15 psi at speed. Temp stays around 140, slightly hotter when idling. I just bought a 1989 race modified 150. Usually has a very powerful telltale. water shoots around 10 feet away. Temp stays at 140 all the time. Twice already the telltale spout has gotten clogged with salt and turned into a weak stream. But the motor still did not get hot. I had to push a small drill bit through the spout a few times with the motor running to clear the clog. Check yours to see if it's just clogged.

[pcrussell50]

Burning scalding hot. Steaming even.

We don’t get much in the way of winters in Southern Nevada. 50’s for a high on the coldest days. And I’ve been maintaining this family of Merc V6’s for about ten years now. If I replace an impeller after three years, it still looks good but I do it anyway.

And water veritably gushes out the thermostat openings when I have the lower off and a garden hose tight on the brass tube.

===

I will of course check the water pump anyway because of the odd chance that the impeller grenaded anyway.

BUT

I wonder if I dorked something up in getting the copper tube attached to the water pump when I was stabbing the LU up into place? There is a white, hard plastic tube sticking out the top of the pump housing about 3-4 inches that I slid the copper pickup into. And I wonder if something went wrong there?

OR

Since this was a powerhead swap from a 2.0 to a 2.4, I wonder if I got something wrong in the adapter-exhaust plate stack and fitting the copper tube to it? Something where a garden hose has enough flow to fly out the thermostat openings in the top of the head, but not the impeller?

-Peter

[Dave S]

Check poppet valve.......if not opening H20 can't do it's job.....

[pcrussell50]

Check poppet valve.......if not opening H20 can't do it's job.....

Is there really enough pressure to push open the poppet spring at 700 rpm idle on the muffs? I thought (and could easily be wrong), that the poppet was supposed to open at like 3000-3500 (tel:3000-3500) rpm.

===

Also, I've had my poppet off twice in the last month diagnosing and fixing a weep out the vent hole, which I did with a new diaphragm. I think I have it right. It's the two-chamber poppet design that has the 90 degree barb and hose that runs up to the top of the block where the fitting for the water pressure gauge goes. When I'm idling this motor and it's hot, almost nothing comes out the 90 degree barb

Sounds like I need to know more about this cooling system. :-/

-Peter

[Chaz]

Peter,
Looking at the first picture .. yes on both side of the combustion chamber there is a lot of build-up in the water channels .
I had two sets of Yamaha heads that had the same issues. I bead blasted the heads and then epoxy primed the water jackets. :thumbsup:

And yes replacing the water pump is a good idea. If nothing else, slip the cover off and take a peak at it ... all the vanes in place and pliable, with no tares .. send it .. ;)

Also for the two chambers shown, it looks as if the piston's for those two holes have dinked the head on the right side. See if the piston's have the same witness marks. If nothing else, it might be so close it won't grow carbon there .. :eek: :D

[Jim Speros]

On this you are being way too analytical, replace the water pump and accept the win. BTDT. :smiletest:

Manual states inspect impeller every year replace every other. Service the water pump. If base under plate has any sign of melting replace it. Make sure the silicone strip is on exhaust divider near water pump. Make sure grommets of both ends of water tube are intact. If it has 15 lbs running, it pees from telltail off idle and no alarm is sounding on tested alarm sender MOVE ON.

[Jim Speros]

Pretty sure the salt dam you speak of is just because of gasket. Something has got to hold the squish ring in position. On jug side is open water passage. I can't say it isn't a good idea to clean it out to prevent decay and future issues but on its own IMO it is a non issue.

[Dave S]

The dammms...... they cause the gasket to deform when salt builds up.......cut them out/away.

[pcrussell50]

OK guys, loud and clear on the water pump. Everything certainly points towards that being suspicious, so you don't have to twist my arm to check it. However based on experience, I will be flabbergasted if it's not pliable, with all vanes, and no tears, and not taken much of a set. But I also hope to be wrong, because it will point to an easy fix if there is a problem.

DaveS, this motor will never see salt again, so that chapter is behind me. ;-)


Manual states inspect impeller every year replace every other. Service the water pump. If base under plate has any sign of melting replace it. Make sure the silicone strip is on exhaust divider near water pump. Make sure grommets of both ends of water tube are intact. If it has 15 lbs running, it pees from telltail off idle and no alarm is sounding on tested alarm sender MOVE ON.

Great reminder of the fundamentals Jim, thank you. Will do. I’m not sure at all that the lower water tube grommet survived the move. When I stabbed in this LU a few days ago, I didn’t even look to see if the lower grommet was even there. I’ll go through the whole pump per your guidance in a few days when I get back. The buzzer has never gone off in this drama even though the weak telltale was scalding hot and had faint wisps of steam. I have tested the circuit by grounding, AND I continuity tested the sensor before and after heating it. It has continuity when hot.

===

Oh yeah… Someone said a few posts ago about checking the poppet (which in fact is freshly rebuilt and verified unobstructed), but… At 700rpm at idle is that enough to overcome the spring and press it open?

-Peter

[rjdubiel]

No, the poppet will not open at idle. You also should not have much water out the tell tale with stats till it gets hot. And when the poppet does open, it dumps water in the mid, not out the tell tale. When was the last time the pump was replaced? What is hot? Get out the meat thermometer or something and get a temp. Some people think water is hot when it is not. Some cant hold their hand in 130 degree water but that is not hot for an outboard.

[Jim Speros]

Hot, F.n hot here. Lake water is 88. 20 straight days over 100. Gonna be 107 ish most of next week. Water coming from an engine at 130 is not likely.

Anyway. Over the years Mercs have peed differently. Some early engines and most Hi pro engine piss like a race horse. Late model 2.5 EFI's barely pee at all until thermosat opens and even then very little at a low idle. Just off idle they will offer a modest stream.

Tell tale is just that. It lets you know it is moving water. It is not at all representative of how much it is flowing. The pressure gauge gives that info.

Pretty sure That's all I have to say about that. lol

[pcrussell50]

Jim, this motor is a 2.4/200. It’s sibling, a 2.0/150 pees like a race horse and I can hold my hand in it same temperature whether it’s 88 deg lake water or 68 degree hose water. Thermostats keep things where they should be. Your knowledge of lake mead conditions is spot on.



No, the poppet will not open at idle. You also should not have much water out the tell tale with stats till it gets hot. And when the poppet does open, it dumps water in the mid, not out the tell tale. When was the last time the pump was replaced? What is hot? Get out the meat thermometer or something and get a temp. Some people think water is hot when it is not. Some cant hold their hand in 130 degree water but that is not hot for an outboard.

I have lots of experience feeling by hand, telltale water streams that are the correct temperature in the 140’ish degF range. I do it all the time and it does not burn me.

This water was scalding hot. Probably close to boiling, based on the small wisps of steam I was seeing even though the air temp was 100degF.

I tested the thermostats in a pan of water before I installed them. The weak and scalding hot telltale behavior was identical, both with and without the thermostats because after the weak and scalding hot flow, I took out the stats and tried again. There was no difference with or without. It was as if the heads were barely filling up enough to let a little dribble out the top thermostat holes.

I do have a proper fast-read thermometer though. Good idea, maybe I’ll bring it.

Pump was new beginning of last season. I have not inspected it this season. And I will. I have found that if I replace the pump after three seasons @20 hours per season, it still looks good, but I still change it.

Before I installed the lower, I put a garden hose on the copper pickup tube with the thermostat covers removed it filled up the heads and was dumping out both openings as I reckon it should.

So this really looks like a water pump problem. it’s just that I’ve never had a problem with a year-old water pump before. I will be shocked if that’s the problem, but I will of course look anyway.

Also:
The buzzer never went off and I tested both the circuit and closing when heated, before installing
did both compression and leak down and they were good

-Peter

[rjdubiel]

water boils at 212, you are not even close and if you were the motor would be done. I am guessing you are feeling about 140-150, maybe even 160. But once you get on the gas it would drop to 120-130 once the poppet opens. Also, you can get exhaust into the water cavities so I am guessing you are not seeing steam, its exhaust. Hopefully it is not exhaust leaking into the motor from heads or divider.

[pcrussell50]

water boils at 212, you are not even close and if you were the motor would be done. I am guessing you are feeling about 140-150, maybe even 160. But once you get on the gas it would drop to 120-130 once the poppet opens. Also, you can get exhaust into the water cavities so I am guessing you are not seeing steam, its exhaust. Hopefully it is not exhaust leaking into the motor from heads or divider.

I put the divider on with fresh gaskets hopefully it’s not that. But maybe. And I leak down tested the heads. All normal leak rates: 95-96 @100psi

-Peter

[pcrussell50]

The heads are still off from the salt cleaning. Gaskets scraped, ready to go back on. But I’ve gone on a trip for a few days. Back Wednesday.

Thanks for everybody’s input so far.

Fingers crossed it’s the water pump.

I’ll report back how it goes.

-Peter

[rjdubiel]

Pull your thermostats housing and fire it up with a new pump. Plenty of water will come.out the heads

[pcrussell50]

That’s the plan. First thing when I get back.

In fact I have already done it with no lower and a garden hose on the water tube. Worked just like you described.

Again thanks to you and all who are providing input.

-Peter

[derekfl]

I think the poppet kicks in around 1800. I found a chunk of rubber in this hole where water goes from exhaust cover to head. Not saying pull exhaust cover, but little pieces of impeller can get most anywhere in there.

[derekfl]

I think the poppet kicks in around 1800.

[pcrussell50]

I think the poppet kicks in around 1800. I found a chunk of rubber in this hole where water goes from exhaust cover to head. Not saying pull exhaust cover, but little pieces of impeller can get most anywhere in there.

As part of my de-salting process, I pulled the exhaust cover inspected, and re installed with fresh gaskets.

I was wanting to make sure the cover bolts weren’t corroded in place. Thankfully they weren’t.

-Peter

[pcrussell50]

Weak hot tell tale solved…


https://youtube.com/shorts/nlpxOZSffio?feature=share

The, “it’s the water pump, stupid”, crowd had it. ;) When I pulled it apart to inspect, the year old impeller was unsurprisingly, supple and healthy and in great shape. The problem somehow was lack of the grommet in the impeller housing. Putting one in, solved the problem it appears.

Many thanks to Jim Speros who specifically named that as a thing to inspect. My housing is black and I had always assumed the grommet was there but never checked.

-Peter

[XstreamVking]

Another trick is to trim away a coil on the poppet spring. Makes it open sooner. Tech at merc school taught me this hack. I have done it and it works. Glad yours was an easy fix.

[pcrussell50]

Another trick is to trim away a coil on the poppet spring. Makes it open sooner. Tech at merc school taught me this hack. I have done it and it works. Glad yours was an easy fix.

Great tip. Might look at playing with it since I have several spare poppet springs.

Now… Just to make sure we’re on the same page, the poppet isn’t supposed to open at or near idle though, is it?

-Peter

[XstreamVking]

It will open a tad earlier. Maybe 1200 r's. I have some extended idle areas where I boat and my 200 EFI even with new parts would go up to 160. Trimmed the spring and it now runs consistently at 145, Which is correct. Try it and see if your engine likes the change. Merc teacher explained some of the springs if tested, were stiffer than others and could cause issues.

[pcrussell50]

It will open a tad earlier. Maybe 1200 r's. I have some extended idle areas where I boat and my 200 EFI even with new parts would go up to 160. Trimmed the spring and it now runs consistently at 145, Which is correct. Try it and see if your engine likes the change. Merc teacher explained some of the springs if tested, were stiffer than others and could cause issues.

Fantastic info, thanks so much :thumbsup:

-Peter

[FMP]

Have a look, telltale's diverter before so holding up flow at those passages would increase pressure against the pump. Typical direction

[derekfl]

ok, where in that schematic does the poppet fit in?

[FMP]

Down low starboard, as fresh cool first enters.

It's probably the water tube seal under the adapter...