Merc 200hp V6 EFI OVERHEATING (1990 roughly)

[bobo05]

hey guys,
firstly for any help i get i thankyou all now.

i have the above motor i have just spent australian $1600 getting it fixed at the local shop to find its still not ready. im running out of cash fast.. i have the boat and motor back home now with overheating as the last problem. i have new head gaskets, been told good compression. motor runs fine starts everytime just takes 3 to 5 mins under idle and it gets hot. he told me to drop the leg put silicone around the copper pipe inside the leg and that should be it. something about the water not getting up or around the top of the motor. or not enough water circulating. does anyone agree with that or have any other ideas that i could try before i go back and save more money for the boat shop.

once again cheers for any help.

 

[TheOzzieMechanic]

Re: Merc 200hp V6 EFI OVERHEATING (1990 roughly)

You say this is the last problem. What was the first? Can you give me some history on the motor. When did you buy it? what problems has it had? how long have you had it? The silicon trick sounds a bit odd. 200 efi or 200DFI? Have you checked water pressure. Has the mechanic put the unit on the CDS or the DDT ? What makes you say it is overheating ? What is the s/n will help if I can.. Ps will cost you a Barra if I can help!!! or a Muddie ...... O.K. a mangrove Jack will do I,m not that fussy

 

[bobo05]

Re: Merc 200hp V6 EFI OVERHEATING (1990 roughly)

ok im not that good with the boat motor lingo but i can tell you what i know..

first problem was when the motor was in the drink running it was kinda studdering then it just stopped. it did not shut down just went into like a limp mode.

let it sit on the banks for a couple of hours and after still had the same problem.

soloution - we had a blown head gasket. had both gaskets replaced and the compression tested, found no compression in cylinder 1 and very little in the other 5. now with new gaskets they have all come up and no.1 cylinder was at 50psi when i took it back from the shop.

the mech at the shop then told me it was overheating due to not getting either any or enough water through the motor.

last night i dropped the leg and ran water up through the tell tale blocked the route down the leg from the t-piece. water seems to be running freely through the motor and out the bottom of the leg. the mech says it copper pipe could well be the problem. something about a grommet under the block would or should fix it but the block has to come off for this to be replaced. secondly we could put some sort of silicone around the pipe and place it back giving us a easy fix. how does this sound. does the block need to come off coz it seems a lot of work for such a small grommet.

details of the motor are a little unclear as i dont know to much about them but i saw a pic of a 1989 motor that looked the same as mine. ive had the boat and motor for about eight weeks and only run it 4 or so times only once in the water and that was for about 1 hour before dramas. the motor has 200hp mercury EFI v6 written on it so im guessing thats what it is.

hope this helps with you helping me..

oh yeah and a muddie or barra wont be a problem.. we are not short of them up here as i have a friend who is a crabber. if we can resolve this drama they are on the way..

cheers

Bobo

 

[bobo05]

Re: Merc 200hp V6 EFI OVERHEATING (1990 roughly)

ok, we have decided to take the block off after some advice from the local boat mech.. may be that the copper pipe running up the water may be leaking. a grommet could fix this problem but the job is not a pretty one. entire block needs to come of in order to get to this grommet. failing this fix ill be up for any ideas ppl can throw at me as after this if its still overheating im all out of ideas..

 

[gss036]

Re: Merc 200hp V6 EFI OVERHEATING (1990 roughly)

After reading this I went looking in my 1989 OEM Merc manual for the v-6 series, they are showing a seal at the top of the copper pipe in the mid-section in the piece called drive shaft house plate. That is probably the one your mech is talking about.
You probable already know this by now. Lot of work to replace such a tiny part.
Are you sure the copper tube is inserted into the seal?

 

[bobo05]

Re: Merc 200hp V6 EFI OVERHEATING (1990 roughly)

yeah is was i think but it sure is now. only problem we have is it seems to be overheating even after taking the block apart and replacing all the gaskets orings seals. the motor gets hot within about 30 seconds. does not seem to get water to the heads. if we unplug the water tubes at either side of the motor and run water in direct while the motors running the engine cools down with whatever side you put the water in.

my qestion now is... i see around the forum something about a poppet. does my motor have one and could this be the problem. also i was told that timming could have a lot to do with this. but water not running through my motor does not seem like a timming problem..

need help guys i want to have this motor on the water next sunday for my lady's birthday.. HELP..... i want to live..

 

[gss036]

Re: Merc 200hp V6 EFI OVERHEATING (1990 roughly)

Yes, you have a poppet valve. It is on the lower starboard side of the block and looks like a figure "8", has 4 small bolts that hold the cover on. The guts are spring loaded but will not jump out at you. The poppet works to dump excess water out of the block at about 2500-3000 rpm. If you are overheating at low rpm, that won't solve your problem but is work a check.

What happens if you run water back through the pee tube indicator hose? Maybe try running water back through the hose from the poppet valve. Kind of a back flush. Obvously your have a blockage somewhere. Maybe a piece of an old impeller stuck somewhere. Take the thermostats out temporarly and see if you get circulation.

 

[bobo05]

Re: Merc 200hp V6 EFI OVERHEATING (1990 roughly)

ok i have replaced the one thing the mech told me was fine. the impellor and what do you know. i now have a great flow of water through my motor. i have replaced alot of gear but i think it was for the best. im gonna have a look at this poppet valve but i think we have it under control as when ideling it appears to be fine and we are putting it in the water this afternoon. hoping all goes well. ill post a comment on how it goes.. cheers for the info on the poppet as stated above ill have a look at it.

 

[gss036]

Re: Merc 200hp V6 EFI OVERHEATING (1990 roughly)

Good to hear that is running cooler. What happens is that the impeller form the natural bend (shape) from sitting tight in the housing, it turns but is not very efficent, about like putting mixer in a can of paint, just stirs it up w/o forcing it up the tube.
I hate to say it, but I sure hope the mechanic replaced the thermostats. paid a guy to do my head gaskets about 4 years ago, then I checked the thermostats and he had not touched them, they were all salted and corrided from the salt water. I called him and ask why not? He said I didn't ask him to check them, ok! Last time I will have him work on my stuff.

 

[j_martin]

Re: Merc 200hp V6 EFI OVERHEATING (1990 roughly)

ok i have replaced the one thing the mech told me was fine. the impellor and what do you know. i now have a great flow of water through my motor. i have replaced alot of gear but i think it was for the best. im gonna have a look at this poppet valve but i think we have it under control as when ideling it appears to be fine and we are putting it in the water this afternoon. hoping all goes well. ill post a comment on how it goes.. cheers for the info on the poppet as stated above ill have a look at it.

Seems to me that if you have spent the time and effort to get close enough to the impellor to inspect it, you might as well replace it. If you're having trouble that in any way could be cause by pump trouble, replace the whole pump. It isn't very expensive.

hope it helps
John

 

[bobo05]

Re: Merc 200hp V6 EFI OVERHEATING (1990 roughly)

ok the poppet valve we have checked and seems to be working fine. the local mech gave us a print out of the part breakdown so we could find it.

the last question i have is what temp at idle and what temp under load should this motor be running at..

if all temps are right we are skiing this weekend as we have put her half in the water to test it and seems to be ok just wondering on temp levels..

cheers

 

[gss036]

Re: Merc 200hp V6 EFI OVERHEATING (1990 roughly)

Your thermostats are set 143 degree "Fainheit" so you should be somewhere around there, maybe as high as 150-155.

 

[bobo05]

Re: Merc 200hp V6 EFI OVERHEATING (1990 roughly)

ok i took her down to the river and she ran like a dream. i said last question last time but i have just one more im hoping. i see the temp you've said but my question is on the temp guage would that be around three quaters as i know these monkeys run a little hotter than usual. she is sitting flat on that setting cooling off a bit down to around half when under load then when ideling jumping back up to three quater. i ask this as i cant get a good reading from a meter and my guage does not have temp reading just quater half three quater and then bang.

by the way thankyou for all your help thus far has been muchly apprectiated.

 

[bobo05]

Re: Merc 200hp V6 EFI OVERHEATING (1990 roughly)

hey i was reading in another post about dirty injectors. after all the work we have done to the motor it is 1. running fairly cooler and seems to do the work across the water. but it still is having problems when we are wakeboarding. starting is a drag as the motor does not want to get going. when you get the boarder above the water the boat shoots off like a rocket and you almost have your arms ripped off. so as i said above maybe it is the injectors or a blockage in a fuel line. so can i clean out the fuel line. if so how and secondly what is the best stuff to put in her to clean the injectors. id like to do both as the old better be safe than sorry rule applies. ive done almost everything else and its getting better just hoping this is the final play..

 

[gss036]

Re: Merc 200hp V6 EFI OVERHEATING (1990 roughly)

You can try to run a strong mix of Cheveron Techron or Seafoam through it to see if that might help out. Otherwise you will probably have to have them professionaly cleaned.

 

[bobo05]

Re: Merc 200hp V6 EFI OVERHEATING (1990 roughly)

im still having a drama getting the boat to get up on plain. by saying that i mean i can give the motor full throttle and she spits and farts until it hits an angle she likes then off she goes. does anyone think that is a timing problem. once on plain i can slow and speed up without a drama. but once at a stop it happens all over again. also can the flywheel be put on backwards as im not getting a reading with the timing light.

as for temp we have her running at a steady 100 to 120. so all seems to be well there. we found and this may help others. the water jacket covers were full of salt. took 5 mins to get them off and helped with the temp problem by ten fold..

 

[j_martin]

Re: Merc 200hp V6 EFI OVERHEATING (1990 roughly)

im still having a drama getting the boat to get up on plain. by saying that i mean i can give the motor full throttle and she spits and farts until it hits an angle she likes then off she goes. does anyone think that is a timing problem. once on plain i can slow and speed up without a drama. but once at a stop it happens all over again. also can the flywheel be put on backwards as im not getting a reading with the timing light.

as for temp we have her running at a steady 100 to 120. so all seems to be well there. we found and this may help others. the water jacket covers were full of salt. took 5 mins to get them off and helped with the temp problem by ten fold..

Do you have the right prop on it? If it's overpropped, you won't have a good hole shot, and might damage the engine.

Be sure the prop allows the engine to spin up the WOT specification. Over revving is better than lugging it. If you have a high bite prop, like a 4 or 5 blade, be sure it has exhaust relief holes in it to allow the prop to slip on takeoff so the engine can spool up good. (sort of like slipping a clutch)

hope it helps
John