T-Stat ?

I got out for the first time last night and I can't get the engines up to temperature. I have Eickert 160 degree high flow stat's in there with factory Merc T-Stat housings, circulating pumps. According to the gauges never went above 145 degrees, had a hand held temp gun with and when I shot the manifold right below the t-stat housing it read 127 degrees. Not sure what to make of this.....should I put 140 degree stats in? With the stats not opening it's screwing with the water pressure. I'm going to install water pressure bypass's in so I won't have to worry about that. Any suggestions????

Both engines doing the same thing?

Yes

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Originally Posted by eightsecmopar

I got out for the first time last night and I can't get the engines up to temperature. I have Eickert 160 degree high flow stat's in there with factory Merc T-Stat housings, circulating pumps. According to the gauges never went above 145 degrees, had a hand held temp gun with and when I shot the manifold right below the t-stat housing it read 127 degrees. Not sure what to make of this.....should I put 140 degree stats in? With the stats not opening it's screwing with the water pressure. I'm going to install water pressure bypass's in so I won't have to worry about that. Any suggestions????

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Hey Clyde. Dont get too concerned with water temps. I know alot of guys with strong car/automotive backrounds, feel that these engines need to see 150-170* water temps, but its really not true.

Running the engine water temps at 100, 120, 130, etc, is just fine. The cooler temps will help keep you away from detonation. Almost everyone I know running blowers, runs no water stats, 100* or sometimes even colder water temps, and cylinder wear/ring wear really isn't a issue.

I'd go with a 140* stat. On our lake, with the cold water, it would take a long time to get a 160 stat to open. Adding a psi relief valve is a good idea. I'd install it before the engine, in the 1 1/4 line that feeds the engine. This way, you'll bleed the extra psi off before the engine block, when the stat is closed. Set it up to when the stat opens, the psi relief will no longer be bleeding off (closed).

Something really trick, that ive seen, is running water to the exhaust manifolds first, before the engines. it preheats the water entering the engine. Ive seen guys with blowers and no water stats do this. Helps to get a little bit of temp in the engines.

So what you are saying is to put it right after the sea pump, before it goes into the oil cooler, right? I'm going to try the 140 degree stat with a bunch of 1/8" holes drilled in it and see what happens. Hoping to get back out this weekend. Thanks for the help!

Id try to install it after the oil cooler. So the oil cooler still gets full cooling water, even if the water stat is closed.

Why drill the holes in?

Because of water temp issues like that, I put the thermostat water coolers in the Scorpion. Appears to help some when the lake is cold.

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Originally Posted by Ratickle

Why drill the holes in?

Because of water temp issues like that, I put the thermostat water coolers in the Scorpion. Appears to help some when the lake is cold.

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You mean thermostat oil cooler??

Oops, duh, yep........

Since there is two threads on temps, and Lake Michigan is colder than heck still, I've been doing some reading to see what others think. Pretty much the consensus is the engine needs to see at least 180 degrees as an operating temperature. Even the results stated on a 160 degree thermostat say they start to open aat 160 and are fully open at 180. Some of what I've read;

One comment.....

Many HP engines now have thermostatic controlled oil coolers and close cooling. When you run the engine oil cold, condensation tends to collect in the valve covers. If the engine oil never nears 212 the moisture doesn't get heated out of the oil. It effects the mixture, engine clearances, and HP. Just another reason not to take off the circ pump and push water straight through. No water temp, no oil temp, no good.

And another.....

A lot of opinions on this but 180-200 seems to be the consensus....marine engines run cooler water temps (than autos) but because they are under such a constant moderate to heavy load, the combustion temps are high enough to help ward off sludge buildup and they run under ideal pure air conditions, there is hardly any dirt on the water....this is why a by pass to the pump is so important for faster warm ups and consistent temps.

And another interesting tidbit I've read several places, but I do not know if it's true or not....

Do not forget that if Raw Water cooled, and IF running in Salt Water, you will have "Salt Crystallization" issues to consider as for engine operating temperature!
Salt crystallizes at/near 145* or so...... so if RWC, and in S/W, the stat selection should be offering engine temperature of around 145*.... and no higher!

If River/Lake....., or equipped with a Closed Cooling system, you will want operating temeratures closer to 160*/170* or so.

I'll also add this to the other thread. But, almost everything I've read, says that if the thermostat and temp gauge are working properly, and the engine is plumbed properly (several articles also mention the check valves used in some Merc IO's) the engine will come up to the thermostat temperature even if you're running in 33* water in Alaska......

Thanks for the info

Anytime. I'm not done digging yet, because I'm not sure about that salt crystalization thing. The other part about burning off the condensation makes sense. I know my engine guy worries about the Vette sitting and wants to always make sure when I start it I run it all the way up to temp instead of just letting it sit and idle for a short period of time.....

My engines would probably last one high speed pass at 200* water temp. My oil temps would probably be thru the roof too. Cars can maintain a oil temp consistant with their coolant at cruise speed, because they arent under a 80% load cruises for an hour straight.

If we're talking about a low compression dished piston 330hp 454, thats one thing, but once you start getting into higher compression, big cammed, high performance stuff, I don't recommend those kind of high water temps. Im not so much talking static compression only, but cranking compression, can also play a big part in detonation. Of course timing, fuel quality also plays a part. Heat is a marine performance engines enemy.

Mercury used 140* stats in their marine big blocks. It worked. Theres a zillion out there running around with 140* water stats, why reinvent the wheel. Put a 140* high flow stat in there and call it good!

Theres a couple things about water pressure that most people forget about, and start blaming crossovers, etc. The exhaust system plumbing. One set of manifolds compared to a different brand, can change water psi readings. Think about it. Psi is the resistance to flow. If the water cant get out fast enough, it will build psi. Also, the pickup design on the transom. Something as simple as having a pickup 1/8" too deep, can raise water psi at high speed. Theres a reason why most of the time, you can sit in nuetral and rev the engine to 3k rpm, and have almost no water psi. then get up on plane, and see 10-15psi at 3k rpm. The water is getting pushed into the system.

I highly recommend running water dumps/steam lines off the back of your intakes, especially if you have a newer style 502. By doing this, you eliminate any steam pockets that may form in the rear of the heads, and helps cool those rear cylinders. Also, by changing the diameter of the lines that dump overboard, you can adjust your water psi. Larger line=less psi, smaller=more.

As i stated, my engines never saw anything more than 120*, mainly the water temp gauge pegged cold. Never had milk in the oil, bearings looked brand new after 6-7 seasons of hard running. Leakdown tests were also good.

Id talk to some engine builders, like Eddie Young, Dean Gellner, Teague, etc, and see what they recommend. I dont believe ive been on a boat with some custom built engines with 180-200* water temps. Just about all of these engines built by these guys utilize a crossover system, and not a automotive style circulating pump.

Not suggesting to shoot for ice cold water temps, but 140-150* is plenty for a N/A engine. 200*, your near the point of boiling the water in the cylinder heads and block. Remember, this is pure water, not glycol in your cooling system (raw water setup) Should you plug a strainer, lose a impeller, etc, while running, your gonna get that engine so hot in seconds, youll be pulling the engines out for major repair.

Running oil themostats is always a good idea, esp where we boat. You do wanna get the oil to operating temp, not only to burn off condensation, but also its just better for lubrication, since oil isnt designed to be continuosly run at say 120*.

Do your engines have 120* stats?


When you're running at 120 or so, what is your oil temp?

One more thought;

If you look up Mercruiser High Performance engines, every one lists a 160* thermostat, 5 863358001 THERMOSTAT, 71°C (160°F). This includes the 850, the 1025, the 1075, and the 1200 SCI. They have no temp range listed yet on the thermostat for the new 1350. Those engines are developing their high peak HP with boost, and all but the 1200 carry a factory warranty.

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Originally Posted by Ratickle

One more thought;

If you look up Mercruiser High Performance engines, every one lists a 160* thermostat, 5 863358001 THERMOSTAT, 71°C (160°F). This includes the 850, the 1025, the 1075, and the 1200 SCI. They have no temp range listed yet on the thermostat for the new 1350. Those engines are developing their high peak HP with boost, and all but the 1200 carry a factory warranty.

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Difference with those engines, they are port injected. Being port injected, you have a major advantage to excellent fuel distribution to each cylinder. Also, they are probably relying on a temp sensor, to tell the ecm the engine is warm or cold.

Clyde here has a carbed old school setup. Comparable to the old HP500's, 454/420's, 500 bulldog, old 575 merc, etc. All of those engines used a 140 stat.

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Originally Posted by Ratickle

Do your engines have 120* stats?


When you're running at 120 or so, what is your oil temp?

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No water stats in mine. Water temp stays around 100-120*. Do have oil stats now, however, ran for a few seasons without oil stats. Oil temps without the oil stats never really got over 150*, and that was on a long run. Bearings, lifters, etc all looked fine when engines tore down last year.

When I bought this boat it had cross overs and no stats, water temp gauges never moved. I was seeing alot of condensation in the top of the engines. When I tore them down though, bearings and related parts all looked good. Oil temps were around 140* if I remember right and water psi was 10lbs at wot. I should of left it that way! The previous owner ran it that way for 10 years and didn't blow it up. I try and put all of the Merc stuff back on to get some heat in the engines and have nothing but problems. I will get it figured out but what a pain in the a**.