V6 200 EFI - Don't trust the telltale!!

[jimc_LA]

Fairly new to this forum, but have gotten some great advice and learned a lot from reading the posts. I really appreciate all of the assistance and have benefitted greatly from everyone's experience here.

I just finished a 4 week long saga resolving troubles from sour fuel in my boat. Replaced many parts - hp fuel pump, o-rings, fuel lines, fuel pressure regulator and thermostats (while I was at it).

Was anxious to get it out on the water today to test it out. Had run in the driveway several times and all seemed right with the world. Of course ,the acid test was going to full throttle. Well launched this morning and it fired right up. Once I got past the no-wake zone i nailed it and it was perfect. no misses, no hesitation, great acceleration. Got through the bayou and the lake was fairly choppy, couldn't run very fast so we were going to head to a structure to fish a while. Not 10 minutes later, I get the continuous beep alarm indicating an overheating condition. Brought it back to idle and looked at the telltale which was strong. Put my hand on it and the water was very hot. Looked at the water pressure gauge and it was barely registering.

Shut it down after about a minute and dropped anchor. Pulled the engine cover and let it cool for a while. After about 15-20 minutes, ran back through the lake to the bayou deciding that it might be better to run fairly quickly as opposed to slow, I kept an eye on the water pressure gauge and listened for the alarm. Planned to shut her down again once in protected water. Had abolut 8-10 pounds of pressure on the gauge. Got to the bayou and after another cool down period ran the remaining 5 minutes to the launch.

Every time I restarted, she cranked instantly. With low water pressure, I'm sure the impeller's out, but i don't understand why I had such a good telltale stream. My engine has been notorious for having a weak telltale, particularly at idle. If the impeller is bad, can I still get a strong telltale?

I've already picked up an impeller kit and plan on changing it out this week, but could this have anything to do with the new thermostats i installed? Purchased the stainless steel versions because the others had gotten so coroded. Other than parts of them being stainless, they looked identicle to the originals. Also replaced the rubber grommets (seals?) that wrap around them. Could the poppit (sp?) valve be acting up? Never had an overheating problem with this engine before this. Impeller was about 3 years old and thee boat hadn't been run in a while (hence the sour fuel issues that started all of this).

Anyone have any thoughts on this?

Thanks.

Jim C.

 

[prockvoan]

Re: V6 200 EFI - Don't trust the telltale!!

Do pull the water pump impeller.If the poppit valve was bad,you would see water coming from the lower motor cowl.There is a tell tail hole on the side of the cap of the poppit valve.

 

[Texasmark]

Re: V6 200 EFI - Don't trust the telltale!!

Seems every engine is different and not familiar with yours. Some the telltale comes directly from the exhaust manifold cover and is not in the stat-popoff loop. Some it is connected to the stat output and you don't pee till the stat opens. Some engines don't have a stat. Some have a stat and no popoff. Manual helps, visual inspection sometimes gives you the answers.

The stat is for low rpms/low pressure conditions. It takes water pressure to unseat the popoff and get decent flow thru the powerhead to sustain high rpm running.

Now let's look at the impeller.

Mark

 

[jimc_LA]

Re: V6 200 EFI - Don't trust the telltale!!

Thanks Guys.

Prockvoan - i am definately going to pull the impeller as soon as parts come in. Found the impeller/seal kit locally but had to order the upper housing (from iboats). I'm pretty sure that this is what my problem is. Ran it quite a bit in the driveway over the last week or so while resolving my fuel issues. Must have gotten dry or maybe I revved it a bit too high. I just wasn't sure why I was getting a great (stron) telltale stream with an impeller gone bad. Water at the stream was definately hot, though.

Texasmark - I'm not really sure where the poppit valve on my engine is or if it even has one. I'm going to search the manual later today and see if it shows one (where would it be located?). I've just seen it mentioned on this and other forums in relation to overheating issues. Considering I was getting a strong telltale stream even while overheating (likely from an impeller issue), I was just suspicious that maybe there's something else going on. My telltale is tapped off of the starbord thermostat return (?) line coming from the head. My engine has a +/- 3/8" rubber hose that comes from somewhere in the lower cowling to the port thermostat, it then jumps over to the starbord thermostat and then travels back down to the lower cowling where it tees and provides the telltale source.

Does anyone have experience with the stainless steel versions of the thermostats? As I mentioned, they looked identical to the originals, just some of the components were stainless (mostly the framework). I'll know soon about the condition of the impeller, but on the outside chance that it is without visible damage, I'll have to start looking elsewhere for the problem.

Thanks again for all of your help. Learning as I go here. Now I know how the VST works and could replace the hp fuel pump with ease. Hope that the water pump/impeller goes as well.

Jim C.

 

[Texasmark]

Re: V6 200 EFI - Don't trust the telltale!!

Your directions are reversed. The water source in these hoses is the stat outlet and it drains into the area under the block in the mid section. Back up several threads where the guy has a pic of a 200 Mariner and is asking similar questions . Read my reply about moving the pee to the exhaust manifold hose.

These engines are supposed to have a poppet and I don't know where it is. Willy or Silver can put you onto it.

I'd move my pee source, like mentioned in thread above and it will give you much more meaningful information.

Haven't seen a SS stat. don't know why they wouldn't work. The frame is probably SS rather than brass. The pellet is probably still copper due to thermal transfer efficiency.

Mark

 

[Silvertip]

Re: V6 200 EFI - Don't trust the telltale!!

Don't confuse water "volume" with water "pressure". Just becaue water is flowing out the tell tale does not mean there is any significant pressure. Water poured out of a bucket has zero pressure. The best place for a water pressure take off is at the highest point in the cooling system possible. This allows any steam pockets to escape and will give you the most accurate reading. If your pressure gauge is simply "Tee'd" into the tell tale hose, you might want to re-plumb it as shown on my engine. While the "Tee" seems to work in most cases, some engines need to have it configured like mine. This is the way I did mine from the git-go so I have no idea if the normal Tee would have worked as well in this case. This engine runs 5 psi at idle and 14-15 at WOT.

 

[Texasmark]

Re: V6 200 EFI - Don't trust the telltale!!

So for you V6 guys, Silver has two spiggots from his exhaust manifold cooling, not his sta outlet, and not his bypass valve.

Since the exhaust manifold gets pumped up first (as you can monitor on your V6), that is where you want your pee tube connected. You can't see it, but his fat tube (3/8" on the left dumps into the midsection, but the pee tube comes off it. The other line (to the right) is his "self imposed aftermarket" water pressure sensor.

Mark

 

[jmburock]

Re: V6 200 EFI - Don't trust the telltale!!

On my engine, the poppit valve is in the same housing that the thermostat is in, consisting a rubber gasket 3mm thick, about 4 cm wide, just under the thermostat. Mine was eroded apart and needed replacement. Is your stainless steel stat the same temperature reading. Did you clean out all the sand/ debris out of the water cooling system. ie. run the motor with the stat out to allow the debris pour out of the motor.

 

[jimc_LA]

Re: V6 200 EFI - Don't trust the telltale!!

OK. Great information.

Texasmark: The ss stats are just as you say, s frame w/copper pellet. I did see the post of the V6 Mariner and it looked similar to what I have. I also understand the flow direction from the stats down through the 2 hoses to the mid-section.

Silvertip: That's an interesting setup. I'm currently out of town, but I'm going to have to study my engine to see if I have a similar connection point. I'm not looking at it right now, but my engine is quite a bit different. I assume I'm looking at the port side? When I get back in town, I'm going to take a photo of my engine and post. My water pressure gauge was installed by the dealer (Travis Boats) when I bought the boat new, so I'm not sure where it takes it's reading. Although I'm fairly certain it's not done as nicely as yours.

jimburock: Is the poppit coming out of the head? I have a stat on the upper portion of each head. Other than the stats, the plugs and the bolts, I don't remember seeing anything else. Again, I'm going to have to study this when I get back home. I did not flush the engine with the stats out, but I see the benefit to that now. I will do it when I replace the water pump. Should this be done using the hose connection at the cowling or with the engine running using the actual water pump? Does it matter? Yes, in addition to looking the same, the stats have the same temp. rating (140d I think).

Also, If I find that the impeller came apart, will all of the little pieces get flushed out of the system by taking the stats out and flushing?

Thanks everyone for the help on this.

Jim C.

 

[gss036]

Re: V6 200 EFI - Don't trust the telltale!!

The poppet on most V-6's are on the lower starboard side, follow the hoses and it is connected there to a cap/plate that looks like a figure "8". It has 4 small bolts. You can take it apart, it is spring loaded but will not pop out on you. Many times the poppet will get crud in it and either stick closed or open. High speed overheat usually is caused by the poppet not opening, allowing the excess water flow down through the exhaust.Not an expensive fix but there is no kit, you have to buy individual parts from Mercury Express.Com.

 

[jimc_LA]

Re: V6 200 EFI - Don't trust the telltale!!

gss036: Thanks. I'm going to check this. Based on your reply, I take it that simply cleaning it after removal will not correct the issue? I read in a thread somewhere in this forum that if a weak tell tale was present, you could use compressed air to blow back through the tube. I disconnected the telltale from the discharge and blew it out using my air compressor. I'm still thinking that my problem is going to be with the impeller, but I guess I could have dislodged some debris and it moved to the poppit? I'm not sure if my problem was only at high speed. It definately overheated while under throttle (about 3k-3500 rpms as it was pretty choppy). My alarm never sounded again on the way back to the dock, but it could be because I ran back with the engine cover off. Still have to tear things apart to get to the bottom of this. I may go ahead and order a new poppit just in case.

I'll post some info after I get things torn down.

Thanks.

Jim C

 

[gss036]

Re: V6 200 EFI - Don't trust the telltale!!

Forgot to mention, makes it a lot easier if you remmove the lower cowling to give to access. Just take out the 4 cap screws and tap the starboad side and it will drop, nothing to disconnect.

 

[Texasmark]

Re: V6 200 EFI - Don't trust the telltale!!

Jim, your connection point is the 3/8 hose at the top of the engine just aft of the flywheel. That is your exhaust manifold outlet just like Silvertips so you can plumb into it. Also that line is where your pee line should be so that your pee registers water pump output, not whether or not your stats have decided to open. See my other comments within a dozen posts of this one on other engines.

Mark

 

[jimc_LA]

Re: V6 200 EFI - Don't trust the telltale!!

Texasmark, I looked at my manual last night and think that I found the connection and hose that you're talking about. Might this hose go from the exhaust manifold (aft of the flywheel) down to the poppit valve? If so, I definately know where it is now.

If this is the hose, I guess I could re-use the existing "tee" that the tell tale currently uses and move it up to this hose instead, replacing it with a straight connection.

Please let me know if this is the likely hose.

Going to try to work on all of this over the weekend.

Thanks.

 

[knotready]

Re: V6 200 EFI - Don't trust the telltale!!

cadet 6:08 thursday night 10 minuites ago i pulled my poppet passengerside [starboard] bottom i have a 1998 200 carbs idle cold power up alarms new t stats impeller same will replace poppet tommorow let u know i don't see anything with poppet next will be heads? poppet i got local 25.00 dollars

 

[knotready]

Re: V6 200 EFI - Don't trust the telltale!!

cadet knotready email ck4times@msn.com 1998 200 2.5 carberated runs hot off idle

 

[92Pro]

Re: V6 200 EFI - Don't trust the telltale!!

I had almost the exact same problems with overheating yesterday you are having. Just purchased a rebuilt engine from a local dealer, and went to the lake to break it in. Right after plaining and less than a 1/4 mile, my temp. gauge read really high. I let it cool down and retried a couple of more times with the same results. I left the lake and took it back to the dealer, they installed a new water pump. Headed back to the lake to test and overheating problem was fixed. This was on a '99 Mercury 200 EFI

 

[Texasmark]

Re: V6 200 EFI - Don't trust the telltale!!

Jim C. You have the right hose. I never located the poppet on the V engine cause I didn't have to, so I don't know it's location. You are probably onto it. All it amounts to is a round rubber cover (over a metal disc) sort of thing with a spring on it that fits into the water jacket. Water pressure unseats it at the higher rpm's/boat speeds. At the lower rpm's the stats control cooling.

The stat is like a dime in diameter and the poppet is like a nickle sort of thing.

Good luck,

Mark

 

[jimc_LA]

Re: V6 200 EFI - Don't trust the telltale!!

I would like to thank all those in this forum that have provided me with advice and their experiences. My parts for the water pump came in Friday and I started changing it out this morning.

Dropped the lower unit without a lot of trouble, set it up in the vice and proceeded to dismantle the pump. I was hoping to find a damaged impeller, but did not. In fact, the impeller didn't really look that bad. I've included a pic.


So after thinkning about all of the things you guys suggested, I decided that my problem must be the poppit valve. So after wrestling to get the lower cowl off and get some other things out of the way, I finally got the poppit off. I seemed to stick in the hole and I had to give it a pretty good tug to get it out. Only thing I could find suspicious was that it had a lot of crud on it, the diaphram was intact and flexible. So I dismantled it and cleaned it up and started to put it back together. Then I spied the grommet within the engine annd decided to remove it and clean it up. Catastrophe!! While trying to get it out, I accidentally pushed it into the engine. Stuck my finger as far as I could into the hole and could feel it. So after about 45 minutes, I finally fished it out with a coathangar wire. After thanking the powers that be, I completed reassembling the poppit valve and lower cowling. Getting the lower unit on by myself was quite a chore, but i finally managed to get everything lined up and it slid right on.

Following jmburock's advice, I removed the thermostats and connected the hose to the upper fulsh connection and let ir run for a few minutes, flushing out the entire system through the thermostat openings. Hooked everything up and changed the hose over to a set of muffs connected to the lower unit. Turned the water on and cranked the engine and let it idle. Water pressure gauge read 13 lbs for about a minute or so until the stats opened, then it dropped to about 8 lbs. I looked and the telltale was pumping good.

Felt the water coming out of the telltale and it was pretty hot. Got my infrared thermometer and filled a cap from a paint can with the telltale water. It registered 133 - 135 degrees, which makes sense since the stats are 143 degree. Water at the lower discharges on either side of the mid section just above the cavitation plate was only warm.

I ran the engine up to about 1500 rpms and the water pressure went up to 10 lbs.

I guess I'm good to go now, but I really wish I would have found something that was obviously broken. Then I would know that the problem was corrected. From what I found, my best guess is that the poppit was sticking. Although I really won't know for sure until I get a chance to run it at speed.

I still plan to re-route my telltale so that it is off of the line serving the poppit so that I will get flow prior to the stats opening. I ran out of time today since this ordeal took about 6 hours. I'm keeping my fingers crossed that I have this thing licked.

Thanks again for all that offered their suggestions. Here are pics of my engine. There's a small grey tube that connects to a fitting in the lower aft picture, that where my water pressure gauge picks up. I'll post again after I get a chance to test.

 

[longshanks]

Re: V6 200 EFI - Don't trust the telltale!!

Hi guys. I am looking at $190 for Mercury's factory water pressure gauge, and connections, for my 50EFI four stroke. Is there any reason I couldn't plumb in some hose to the top of my block, such as Silvertip has done, and hook up a non OEM gauge? Looks like some hardware shop fittings, and rubber water hose should do it. As far as gauges, will any run-of-the-mill water pressure gauge work? Or will I need a Quiksilver/Mercury marine gauge?

longshanks