T stats .....does a 1994 model V4 90hp

[1FASTLASER]

My seloc manual is quite vague on this issue. I got a 1994 model V4 90hp crossflow (flatback) have T stats?? If it does where are they located. I feel like they are sticking cause I dont have warm water at all times coming out the peehole. There are times I even get almost straight air coming out of them. Thanks in advance.

 

[Texasmark]

Re: T stats .....does a 1994 model V4 90hp

You need to follow back down the pee line to see where it comes from. If it comes from the exhaust manifold (in the inner V area under the ignition parts) it pees as long as the pump is pumping.....and has had time to fill the engine with water.

If it connects to the heads then you will have to wait for stats to open for pee.

On the V6 Mercs the pee line comes out the back of the stat cover, one on each bank of cylinders. On my '75 70 hp Rude, and my current Merc 90, the water jacket cover has a small cover bolted to it, near the top of the large cover that covers all the cylinders. Under that cover is the stat. Really feel that this late in the game they would have a stat in your engine; especially when there was one in my '75; course my 75 was from the looper revolution (redesign) and the old crossflow V's may have been left out. Just look, you'll find them if there.

Mark

 

[OBJ]

Re: T stats .....does a 1994 model V4 90hp

Welcome 1FASTLASER!

Indeed they have t-stats. Look below the exhaust cover (flatback) and you will see a cover with hoses coming from it and attaching to the heads. Three bolts hold it to the midsection. The t-stats are there.

Because of the path of water flow, the pee stream may appear warm most of the time because the water path goes to the exhaust cover first and will pick up a little heat there. If at times you are just getting air, it could be because of a bad pump impeller, the block is filling with water or the water pick ups are not far enough in the water.

Check the block for temp at idle. You should be able to lay your fingers on the flat area on top of the block just forward of the heads, for several seconds with the engine at temp. If the block seems cold all the time, could be the stats are stuck open. If hot, bad stats, impeller or both.

Do remember, there are two stats. One for each head. One stat can fail while the other is operating normal. This means that one head can overheat/stay cold while the other operates normally.

 

[1FASTLASER]

Re: T stats .....does a 1994 model V4 90hp

I definatley appreciate the welcome AND the advise. Went out pulled 2 hoses and 3 bolts and VOILLA. There the little buggers are. Well time to get my parts guy to order and as well install new impellar while I am at it. Motor never does seem to have a warm flow from the pee hole so I am assuming that the T stats aren't opening as they should. I do know that the impellar is in need of replacement. The pee stream is not near as strong as it should be. Prolly gonna add a water PSI Gauge while I am at it. Thanks again folks.

 

[OBJ]

Re: T stats .....does a 1994 model V4 90hp

You will never or should not get a very warm flow from the pee stream. Although it goes into the exhaust area first, the tap for the pee is taken off before it can pick up any really appreciable heat. Warm yes, but should not be hot.

 

[mikesea]

Re: T stats .....does a 1994 model V4 90hp

Be sure to put never seize on those t-cover bolts. Your lucky to have gotten em out. In Fl.salt water,its a son of a beach on most of em.Usually break.

 

[Texasmark]

Re: T stats .....does a 1994 model V4 90hp

Hey OBJ. Since you seem to know your way around OMC, are there two temp sensors on their V engines like on Mercs? Like you said, if one fails, you want to know it and the only way you can do that is with a babysitter on each one.

Thanks,

Mark

 

[OBJ]

Re: T stats .....does a 1994 model V4 90hp

Sure are Mark. One in each head. Just look for the leads protruding from the heads.

 

[Texasmark]

Re: T stats .....does a 1994 model V4 90hp

Great. Thanks,

Mark

 

[emdsapmgr]

Re: T stats .....does a 1994 model V4 90hp

When you have the thermostat housing apart, check the valve body. There are two very small holes, both of which must be open. They often fill with debris and will cause overheating at idle.

 

[OBJ]

Re: T stats .....does a 1994 model V4 90hp

I usually drill them holes out and make them twice as large at least. Keeps them from plugging up so quick.

 

[Alman]

Re: T stats .....does a 1994 model V4 90hp

Hi, just saw this thread while I was searching for something else, had to register so I could reply to it.

1 - NEVER use never-seize on these engines, especially around salt water, you will guarantee that the bolts will become at one with the surrounding components. Never-seize compounds contain among other things copper, graphite, zinc etc. Galvanic action in seawater will cause huge problems here - especially on the longer bolts that secure the thermostat housing to the cross-vee series of OMC engines. Use a good gasket sealer on the threads (permatex #1, OMC gasket sealing compound, or a good heavy grease) and you will save yourself a lot of grief. Same goes for propshafts, neverseize is the worst thing to use here in salt water, use grease instead.

2 - There was a service bulletin issued around '87 or so that recommended blocking one of the bleed holes in the thermostat housing to improve circulation in the heads. I don't recall off the top of my head which one it was, but don't enlarge them, you'll just cause more problems. If I can dig it up, I'll post it here.