Removing T-stats and Poppet Valve

**vector mike** · 10-01-2002, 10:37 AM

What is the advantage when you remove the t-stats and the poppet valve and replace the t-stats with 1/8" fender washers from the stock setup? I see alot of people on here doing it but nobody says why.

**Talon2.5** · 10-01-2002, 11:59 AM

my motor ran hotter than i liked and then ultimately stuck a piston so thats why i did it to get it in the temp range i wanted for the rpm run out of it

**vector mike** · 10-01-2002, 12:01 PM

Why was it running hotter than normal? Is it from increasing the compression or from the timing?

**Talon2.5** · 10-01-2002, 12:50 PM

well i bought it and 2 weeks later it blew up, i didnt dig into it until then and found nothing in the thermostat area at all and no diverters and a nasty corroded poppet vale in it so i put it back together the way i like it and been good so far

**vector mike** · 10-01-2002, 12:55 PM

If I should do this to mine. I don't have an overheating problem now. I'm going to be cutting my heads soon and was wondering if compression is something I need to watch out for in causing it to run hot.

**Talon2.5** · 10-01-2002, 12:57 PM

it didnt run hot at around 5000-6000 rpm but when i ran it up to 7000+ it would get hot the way it was plumbed

**MTCM** · 10-01-2002, 01:22 PM

If it ain't broke........don't try to fix it.

**vector mike** · 10-01-2002, 01:24 PM

I'm not trying to fix it, just trying to prevent it from happening.

**Talon2.5** · 10-01-2002, 01:32 PM

if the motor runs cool now let it be, if it starts running hot as you "tweak" on it then start cooling mods

**WATERWINGS** · 10-01-2002, 02:09 PM

I can bearly get either of my two temp guages to move off of 120 degrees at any RPM, and trying to lose some pressure, 25-28 psi at WFO.

200 merc
two diverters per side
no poppet
two piece exhaust plate
two dump hoses

WATERWINGS

**B.Mac** · 10-01-2002, 02:36 PM

My motor runs 145-155 water temp. Hot horn does not go off. It's gotten better w/ new impeller as my volume increased. I put a candy thermometer under my dump hose and it reads @ 145-155 with my gauge at 12 o'clock. Sometimes when running at slow speeds underway my gauge creeps to 1 o'clock+ (no #s).
Can anybody describe the procedure to go from a stockie w/ stats to washers, twin dump hoses & no poppet? I wanna run cool. I don't want to wait 'till after it's scrap metal.

B.MAC

**MTCM** · 10-01-2002, 04:42 PM

The older Merc V-6 water temp should be no than 140 degrees. The Cylinder Head Temp should be no more than 180 degrees. I have two 1988 engines here (a 2.4 175 and a 2.4 200). These two engines are healthy, good running engines. The cooling systems have never been modified. The T-stats are installed and the hose routing is stock, poppet valves installed. With the engines on the water hose, at idle, the cylinder head temp fluctuates between 140 to 170 degrees on Gaffrig Temp Gauges. This fluctuation I expect is being caused by the T-stats which are opening at approx. 140 degrees water temp and subsequently closing at approx. 130 degrees (as designed). At this time I have used a Laser Spot Radiometer and a trusty "candy thermometer" and have found that the water discharge (pee-stream) is approx. 125 to 135 degrees. Water pressure is about 2-3 lbs on the hose. In the water at WOT (6000 rpm) the Cylinder Head Temps are approx. 150 to 165 degrees and the water pressure is 20 to 25 psi, nominally about 22psi. I suspect that these are acceptable figures as these engines are still running strong after damn near 15 years, and have a few hours on them.

John Mason...........your engine is too cold! I tried the old "remove the stats and the poppet" back in 1994 on the 200 and it would never warm-up. It idled rough and ran like crap as well. I put the stuff back and the engine was fine. I have heard over the years that too cold can cause premature piston ring and cylinder wall wear. Specifically the chrome bore engines.

Like Skip said, if she is cool enuff now then leave it alone. If you have a mod motor and spinning 7000 or more rpm then it may be necessary to mod the cooling system as Skip has. Otherwise, leave it alone.

B. Mac your numbers look good.........

Look guys, I ain't no expert. I am a regular guy who has owned few O/Bs over the last 24 years, mostly Mercs. These comments are merely some observations. Every set up is different as you all know.

**Talon2.5** · 10-02-2002, 09:53 PM

Look guys, I ain't no expert. I am a regular guy who has owned few O/Bs over the last 24 years

i read your posts, you have good answers and what you posted above looks pretty damn accurate to me!!

Every set up is different as you all know.

thats pretty damn true too!! wieght, set-up, engine health all play a part, as well as ingested debris, sometimes it's as simple as doing a "cleanout" of the system and leaving it alone

**Talon2.5** · 10-02-2002, 10:03 PM

Bmac,

pull the thermostats, put in washers with a 3/16 hole, pull poppet valve cover and take out the guts, drill and tap a hole in the cover to put a brass elbow in it, fill the small hole in the cover that leaks when the valve goes bad, connect a piss tube hose to the brass elbow and out the cowling pan on the starboard side

connect the starboard side head to the port side head and run the the piss tube down and out the cowling pan on the port side

install diverters under the heads above the lower 2 cylinders

NOTE: the one piece midplate is the best to use in this modification, it comes from the factory with the poppet area blocked off so the water doesnt automatically just run straight into the mid section (hard to explain) the 2 piece is made to work in conjunction with the poppet valve with a triangular hole below the poppet to dump the water into the mid-plate where the one piece doesnt have that triangular hole or actually the pan from the offshore cowlings blocks it off