PDA

View Full Version : Replaced My LT-1 water pump


DrJ
07-26-2005, 04:23 PM
On the water two weeks ago in my 1996 prostar 190 and I noticed water dripping from the back side of the Lt-1's water pump. At first I did not think much about it, but would check it every hour or so. As the weekend went on more and more water was pouring out. I haulde the boat home and ordered a new water pump from Checker (the nearest MC dealer is 450 miles). Had the new pump the next morning and the install went very smooth. reattached all of the hoses and tightened all clamps. Took the boat to the lake this weekend and put it on the water. Started it up and had water shooting out of a fitting on the front starbord side of the new pump :eek: . Thought that I forgot to attach a hose but could not find a loose one. Used some comon sense and jerked my drain plug out of the in floor ice chest and luckly it fit perfectly into the extra fitting. It worked perfectly for the weekend. Anyone had this same problem and can anyone tell me what should attach there in a corvette? My boat does have a heater but all of the hoses are accounted for. I am at a loss here. Any help would be appreciated.

NatesGr8
07-26-2005, 09:00 PM
Post some pics. And check the old one to see if it is plugged up too. I am very interested in how the install went since i will be doing the same thing this winter. My water pump has been leaking for the past few weeks now. How much did you pay for your pump?

Nate.

JimN
07-26-2005, 09:23 PM
DrJ- as I said in the other thread, you need to make sure the pump will provide "reverse cooling". If the water goes into the block first, the heads will definitely melt, and they're in the range of $1500 each. I would hate to read that you cooked your motor. If you need a pump, I believe SkiDim sells the correct one and they can answer any other questions you have.

jimmer2880
07-27-2005, 06:17 AM
In a car, the heater runs from the intake to the water pump. In boats, some (but not all) heaters run from the intake to the main water intake line before the water pump. I bet it's a port for the heater. Also - listen to JimN - sounds like you have a non-marine water pump. I'd hate to see you melt and /or warp your heads.

Engine Nut
07-27-2005, 11:09 AM
On the water two weeks ago in my 1996 prostar 190 and I noticed water dripping from the back side of the Lt-1's water pump. At first I did not think much about it, but would check it every hour or so. As the weekend went on more and more water was pouring out. I haulde the boat home and ordered a new water pump from Checker (the nearest MC dealer is 450 miles). Had the new pump the next morning and the install went very smooth. reattached all of the hoses and tightened all clamps. Took the boat to the lake this weekend and put it on the water. Started it up and had water shooting out of a fitting on the front starbord side of the new pump :eek: . Thought that I forgot to attach a hose but could not find a loose one. Used some comon sense and jerked my drain plug out of the in floor ice chest and luckly it fit perfectly into the extra fitting. It worked perfectly for the weekend. Anyone had this same problem and can anyone tell me what should attach there in a corvette? My boat does have a heater but all of the hoses are accounted for. I am at a loss here. Any help would be appreciated.

I have attached a drawing showing the cooling hose hookup for a raw water cooled LT1. This drawing does not show a nipple that would have had a rubber cap-plug on it when we built the engine that is to the left of and below the fitting indicated as number 1 on the drawing. That fitting is used as a return for a heater.

Engine Nut

DrJ
07-27-2005, 12:09 PM
The picture is a great help and I think you are right about the extra on the auto pump being for the heater return. I am still confused about the "reverse cooling". does the water actually move through the pump differently. Or, is it simpily going to wear out faster? this is a pic of the pump I installed and you can see the extra fitting.

jimmer2880
07-27-2005, 12:28 PM
The picture is a great help and I think you are right about the extra on the auto pump being for the heater return. I am still confused about the "reverse cooling". does the water actually move through the pump differently. Or, is it simpily going to wear out faster? this is a pic of the pump I installed and you can see the extra fitting.

Don't quote me - but I believe the water comes into the water pump (from the raw-water pump), then into the block. Then out of the block & into the Heads. In a car, it would be heads first, then block.

DrJ
07-27-2005, 02:13 PM
I called up Mastercraft boats of Arizona in Phoenix. Spoke with the service dept. and this is what they told me. Since the LT1 is no longer in production it is very rare to come across a marine version of the pump. Even Mastercraft headquarters has a very hard time coming across them. According to them if one goes out you can use the auto version as a replacnet. All you need to do is plug the heater return. When I asked about the reverse pumping of the marine model he said the only time you would have to wory about it is if you are running in a warm water area. Our lake temps here in NM stay well below 70 degrees. Hope this helps other prople out there who run into the same problem. :)

Storm861triple
07-27-2005, 02:22 PM
If the pump fits on that motor, and it does, then it is the right direction cooling. The "Reverse flow" means that the coolant goes from the pump outlet, into the heads FIRST, then throught the heads, down into the block, and out the front of the block. This allows higher compression w/o detonation due to the cooler water keeping the heads cooler. The heads warm the water so the water around the cylinders is a more uniform temp, allowing for reduced emissions, better combustion, and more uniform cylinder expansion. -All compared to a standard cooling engine in which the cold water enters the block and goes up through the heads and out the front of the intake.

You can't get a "regular flow cooling" water pump that will bolt onto an LT1 block. It doesn't exist, so you won't be melting $3000.00 heads, IMO. No offense, but who pays $3k for a stock set of LT1 heads anyways??? For half that money, you could have a nice set of AFR's...

-Tom

Thrall
08-02-2005, 11:21 AM
I believe Tom's correct. If you bought a h20 pump for a LT-1 (car), it will be the same as the boat, because they both have reverse flow cooling.
I think the only difference besides the heater output, is the marinized versions have different seals and may last longer because they're designed to be operated in less than ideal water (open cooling system).
Not to threadjack, but where in NM are you? I just moved to Albq a few months ago. Boat mostly at Santa Rosa Lake and Sumner lake.