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mgs96ps
05-10-2013, 11:15 PM
TT members,

I am trying to do research before I order parts to replace both thermostats on my new to me 96 prostar 190 with LT1.

Questions include:

(1) does the 160 T require a gasket between water pump and T housing?
(2) does the 160 T require an o-ring inside T housing?
(3) does the 140 T require a gasket?

Thanks for your help.

Table Rocker
05-10-2013, 11:20 PM
1) No, see #2
2) Yes, it is an o-ring that is sliced to fit around the edge of the thermostat
3) Yes, triangular paper type.

mgs96ps
05-10-2013, 11:40 PM
Thank you Table Rocker.

O ring only for 160 and paper only for 140. Do you use any gasket maker on either?

mgs96ps
05-10-2013, 11:57 PM
Can't seem to find the o-ring on inboard online. Any suggestions would be great.

blackcreek
05-11-2013, 08:05 AM
Any auto parts store is going to have one, fel-pro gasket 35710

mgs96ps
05-11-2013, 08:17 AM
thanks blackcreek,

please comment on post #3

blackcreek
05-11-2013, 08:24 AM
No gasket maker on the o-ring gasket is needed. If the triangular metal housing for the 140 t-stat is corroded clean it up with some sandpaper and use a light film of gasket maker on the gasket.

Table Rocker
05-11-2013, 10:14 AM
I agree with a light film. I usually put the thinnest possible layer of rtv blue. Just put a little on your fingertip and wipe it on.

mgs96ps
05-14-2013, 06:14 PM
I would love for someone to explain and/or correct my understanding of the water flow from lake to exhaust on the LT1! (no heater and no shower)

Here is what I know so far:

-into boat via inlet port in hull
-pass trans cooler
-into raw water pump pass impeller
-up into mixing unit where some slips pass closed 140T to cool manifold but majority goes into main water pump
-main water pump and into block and heads
-at 160 water temp main thermostat opens sending hot water back to mixer
-after mixing if water temp is above 140...thermostat opens and out to manifolds, otherwise back into main water pump

mgs96ps
05-14-2013, 06:44 PM
Another question from a new owner of a 96 Prostar with LT1.

I have seen pictures with hose bibs on top of mixing unit, in front of main water pump.

Is this used to run boat on hose? If so, do people remove impeller to run this way?

Thanks

blackcreek
05-14-2013, 08:06 PM
http://mastercraft.com/teamtalk/showthread.php?t=31626&highlight=coolant&page=5 Read the entire thread. Post 49 shows the coolant flow.

Table Rocker
05-14-2013, 08:06 PM
I would love for someone to explain and/or correct my understanding of the water flow from lake to exhaust on the LT1! (no heater and no shower)

Here is what I know so far:

-into boat via inlet port in hull
-pass trans cooler
-into raw water pump pass impeller
-up into mixing unit where some slips pass closed 140T to cool manifold but majority goes into main water pump
-main water pump and into block and heads
-at 160 water temp main thermostat opens sending hot water back to mixer
-after mixing if water temp is above 140...thermostat opens and out to manifolds, otherwise back into main water pump
You have it pretty well understood. When the water goes into the back of the mixing unit, as much water as possible goes through a 1/2" or so hole into the front side of the mixer and into the manifolds. Water really can't go into the block at that point because the thermostat is closed and the block is already full of water. Some will go through the drilled hole in the thermostat and some will go out the steam vents. Water should start coming out the exhaust flaps soon after starting the engine.

When the engine thermostat opens, water will enter the circulating water pump inlet which will force an equal amount out the circulating water pump outlet and into the back side of the mixer. The water going into the engine will now be "mixed" water. When the mixer thermostat gets to 140, it opens allowing more water to the front of the mixer and out the manifolds.

The thing to remember is all water exits via the manifolds and any water going into the circulating water pump replaces an equal amount coming out of the circulating water pump.

That's the way I understand it anyway.

Table Rocker
05-14-2013, 08:08 PM
Another question from a new owner of a 96 Prostar with LT1.

I have seen pictures with hose bibs on top of mixing unit, in front of main water pump.

Is this used to run boat on hose? If so, do people remove impeller to run this way?

ThanksThat hose bib is for the heater only. Open it up to flow water to the heater core. It's not a great location for hot water since it is coming off the mixer.

mgs96ps
05-15-2013, 11:59 AM
Just when I thought that I was understanding the water flow for the LT1...blackcreek attached the image below and I had to start over, as I was thinking that the housing, (@ 160T), was an outlet for hot water, (like most cars), when it really is an inlet for mixed and/or cold water. The olny thing that I am still not fully understanding is how the 160T can be closed and still let water pass into circulating pump. This must be where the drilled part comes into play...however, if closed, how do the hole/s let enough pass into circulation pump.

Table Rocker
05-15-2013, 12:21 PM
Just when I thought that I was understanding the water flow for the LT1...blackcreek attached the image below and I had to start over, as I was thinking that the housing, (@ 160T), was an outlet for hot water, (like most cars), when it really is an inlet for mixed and/or cold water. The olny thing that I am still not fully understanding is how the 160T can be closed and still let water pass into circulating pump. This must be where the drilled part comes into play...and how the drill hole/s let enough pass if closed.

The circulating pump is sucking water out of the block and pushing it back in the heads any time the engine is running. Just like a car circulates the water through the engine even when the thermostat is closed, so does your boat.

The thermostat on your boat just opens to allow "outside" water into the circulating system. On your car, the thermostat opens to allow water to flow through the radiator.