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I bought this engine 1 year ago. it didn’t have thermostats or a popit valve in it when I bought it so put all new back in and it throws the overheat alarm when go about a 1/4 throttle but it will idle fine. How do I tell if it’s the one exhaust or 2 exhaust. I’m a newbie as well so take it easy on me lol
And is there a way I can tell without taking the power head off
Welcome to the site. Don't understand 1 exhaust or 2 exhaust. Are you meaning 1 pc adapter plate as opposed to 2 pc adapter plate?
Rock
Yes sir sorry about that
You have a two pc adapter.
Rock
Alright I didn’t know if there was a reason it didn’t have the t stats and no poppit valve. it also has the screw in the poppit valve and t fitting coming from the popit valve out the motor.
It has 2 piss holes.
Is that really an '88 200? Shouldn't the exhaust divider cover and (two-piece?) heads be painted black???Quote:
Originally Posted by rock
Attachment 532871
Looks like a high strung performance engine that might have been on a 1 piece plate in a previous life, with no poppet, or thermostats.
The engines I have experienced with two piece plates, have the poppet hose go to the top of the block, or the poppet cover has a plug with no hose. The hose that comes from the thermostats has a T to the adapter plate, and telltale. Your plumbing might have something to do with overheating? What is your water pressure?
What happens at 1/4 throttle, is the timing is fully advanced, and the engine is under extreme load. This makes heat, or even detonation. If this is something that is done often, or for long duration you should lower the timing, and run a smaller prop. That thing likely has a little more timing than your average fishing engine.
Could they have drilled the plate and done the cooling mods I have seen in other threads?
I did replumb it the way you said after I put Tstats and poppit valve in it. I was thinking they have done the 2 plate dry stack mod. Can someone send me a good water pressure and temp gauge I mine don’t work on the boat at the moment as you can the water gauge hose was dry and broke off but I know the water pressure gauge and temp gauge don’t work.
I was somewhat confused by the bare block and 1 pc heads also. If it's an 88 200 it's certainly not a fishin motor.Quote:
Originally Posted by David - WI
Rock
Where do you tell exactly the year model?
There’s two large letter stamps on the block near the throttle arm and a frost plug looking deal on the top of the block with numbers and whatnot. Post those and the fellas here can tell you what the block started out as anyways.
My thoughts as well.Quote:
Originally Posted by rock
Og787233
So I’m guessing it’s a 1987 then?
So were there no numbers or letters behind the timing arm?
Rock
Lucky bastard that’s a 225 promax block. Gotta run the good fuel in that one. No ethanol 91 oct minimum. Might want to pull a head, cc it and measure the head gasket thickness. Could be your issue right there
Does look like an NN stamp. Can you show a pic of the side of the engine.
Rock
Congratulations!!! you got a nice motor!!!
Serial number that starts 0G7***** Is probably a 1997 or 1998
0G3******* is a 1996. So, it has to be newer that that.
I will get more pictures tomorrow if I need more to help y’all out.
That is what is commonly known as a Frankenmerc. Definitely a 225 Promax block but with carbs. And no fuel pump.
Rock
So needs to have a electric fuel pump?
A couple more questions should I run it with the tstats and poppet valve? I also put a different lower unit off a Mariner 150 i was wondering if that could be some of the problem? Any and all help would be appreciated.
The 150 gearcase probably has 2:1 gears in it (a 225 Promax has 1:87 to 1) not a huge issue and makes no difference in respect to cooling. The Promax is designed to run with stats, a poppet and a 2 piece exhaust plate, it's a "consumer" high performance motor not a race motor. Race motors have 1 piece exhaust plates no stats or poppet, turn a bazillion RPM and blow up a lot. 2 million idiots in this world yank the stats and poppet in a fishin motor "cause that makes it a race motor" but it doesn't, however it does make them blow up.Quote:
Originally Posted by whitehead249
All that said, you're in a tough position. You have a great short block but it's an EFI motor converted to carbs. A motor like this needs somebody with lots of experience to get it sorted.
I would start with a good water pressure and temp gauge (verified with a heat gun on the heads). Replace the water pump assembly (never overlook the simple stuff). Post your temps and pressures at idle, 3000 RPM and 5500 or so if it's not running too hot.
Next I would shop for a 225 Promax exhaust plate that's not been molested. The exhaust plate sits under the powerhead and shouldn't be confused with the exhaust divider that sits under the coils.
Once you've done that you'll have a chance to straighten this thing out. The reason somebody ran this with no stats or poppet is because they were created a massive compensation for some other design error in the Frankenmerc process.
That was well explained and great advice. Transomstand could he use a gen 2 or 3 2L two piece exhaust plate and either shorten the tuner or replace with a 200 or Bob's tuner
Certainly possible but in this case I'd want to get known correct stuff under it for a start. Just makes it easier to figure what other surprises might be there.Quote:
Originally Posted by Baker343
Alright I’ll try the easy stuff first and go from there. Is the 225 pro max exhaust plate about 700$?
Wouldn't surprise me if it was for a new one but I gotta think you could do a LOT better than that for a clean used one.Quote:
Originally Posted by whitehead249
Isn't there a grommet/bushing in the bottom of the exhaust plate that seals the water tube... seems like people lose or forget those and can never build water pressure?
I believe it's the same one that's in the impeller housing
Yes, and all that needs to be looked at. We need pressure readings to see if it's leaking or plugged up someplace.Quote:
Originally Posted by David - WI
CorrectQuote:
Originally Posted by Baker343
Very common for one to be missing.
Rock