Strick

Here is how I installed my Mez HD pump:

https://www.corvetteforum.com/techti...=231&TopicID=2

It's long, but covers what you need. You might have an intermittent problem with the pump itself. Call Meziere and tell them about your problem. They'll probably send you another one in exchange.

BrianCunningham

I've been running a 160 stat for 8 years now and love it

grinditout

I am too.
with my work and upgrades, temp hand sits at 185 all day.

Maybe cracked heads/ blown gasket starting.

But I would buy a new rad and thermostat, change switch from fan relay setup, clean steam tube and fittings, then try again, for success.

93 ragtop

If you are using the power side of the fan relay, and not the signal side, that may be your problem. I think that the fans drop out at a pre set speed regardless of temperature.
Im trying to remember how I did mine, but I think I used the pink wire for + signal , which is only hot when the switch is on. Then I grounded the other side of the relay to complete the switch side of the new relay. I then ran a hot wire from a terminal located behind the battery to the new relay (power side) and then out to the pump. Then I grounded the other wire coming from the pump.
In short the fan relay keeps the positive on all the time the switch is in the on position, and then it makes or breaks the ground through the temperature switch or computer based on a call for ac or to turn off due to vehicle speed etc.
Hope this makes sense!!

STL94LT1

Same here.

jonecap

I'm pretty sure you are wired into the fan relay that will cut the 12 volt signal when the second fan comes on, which explains why it takes a while before you have the problem and its infrequency.

Wire it into the lower right relay as you are looking at the side of your radiator and problem should be solved...assuming I am correct.

Good luck.

Bluewasp

I would check your wiring. My car has gotten hot due to a wiring issue. The problem wasn't my fault as in a install issue but rather the poor quality of the connectors offered by summit racing. I guess the wiring kit was made in CHINA but the wiring for the relay harness/plug was defective and the connectors would loose connection to the relay and the pump would turn off. took me a while to figure it out because when I stopped the pump would run until one time the pump was off. I touched the relay and the pump kicked back on. I jiggled the rely and the pump would click on and off...... I looked closer and saw the wiring was backing out of the harness. Cheap plastic crap.


I would check the connections on the relay and go from there.

Why did you install the pump in the first place?

PDQUIK95

Ditto on the fan relay( pink hot wire) for feed to activate your pump relay.
RG:

Rick,
On our 95s, the fan relay pink wire is an (ignition on only) wire that can be used as a feed to activate the pump relay only if desired. Just check it to verify. Using it to actually run the pump though would not be advisable due to too small of a wire size for pump current required.
Rick

Nathan Plemons

I would follow the advice of the others here and check that you might have a wiring problem. Your fan relays look slightly different than the fan relays on my 92, so a generic "pick the pink wire" statement might not always be right. What you need is the wiring diagram so you can figure out for yourself which wire to tap for your relay.

You need something that is hot when the key is in the ON position, regardless of anything else. You could have wired it to the output side of a normally closed relay, that is opening when you reach a certain temperature or condition and thus causing the problem. As you've said, the boiling coolant is really loud so you might not be able to hear if the water pump is running or not, so here are some tips.

1. Set your digital coolant gauge to measure temperature. The analog guage is fed directly from the cylinder head sensor and goes nowhere else, the digital gauge is fed from the sensor on the water pump housing. If your water pump fails, you will see the analog gauge will start to go up really fast. The digital gauge might actually fall a little before it starts to creep up.

2. Wire a light in parallel with the water pump into the cabin. If the light is still on and it still overheats, you might have an intermitten problem with the pump itself, not the wiring.

3. Pay attention to your coolant flow. When it is properly connected and the engine is stone cold you should be able to remove the cap from the coolant reservoir and see the water flow. It is sucked out of the bottom and returned through the very small nozzle looking thing, you will be able to see it shooting out sideways, unless the coolant level is too high but you should still be able to see the disruption. If you put your finger in there you will feel a very strong spray like a jet.

If you follow step one you can see if it is overheating because of pump failure. If you follow step 2 you can pinpoint the cause of the pump failure, be it the pump itself or the wiring. BTW, put the thermostat back in! For one I'm not sure how you would actually seal the housing without a gasket in there so it will likely leak on your opti. Second, if you think the thermostat MIGHT be the problem, replace it. It's too cheap to risk it, and as others have said, you don't want the 160 anyway.

I feel your pain because I've been there. I put a Meziere HD pump on my car some 7 years ago. I love it, but I had a few growing pains. My pump first came with a quick disconnect coupler that was not weatherproof. Every now and then the pump would just quit working and I could see the analog gauge start to spike just like I mentioned and the digital would either fall or climb much more slowly. I was able to get off the road really quickly each time and wiggling the connector would usually make it come back and the temps would drop like a rock. I eventually just cut out the quick connect and hard wired it. I had problems again and it turned out that my WP relay had gotten wet and quit working. I got a different relay with a proper relay base and put it in a place where it won't get wet anymore and have had the same relay for the last 6 years.

Finally I had a problem with the pump still cutting out. I found that I could wiggle the wires going into the pump housing itself and it would come and go. I ordered a new pump and swapped it out, this one came with a nice weatherpack style quick connect. I installed it and have not had any more problems. I know Meziere would probably fix mine, for a fee, but I decided to investigate it myself. I took the pump apart and found that the wires leading into the pump and connecting to the terminals were in pretty bad shape. I attributed this to my fault. I had wiggled, moved, kinked the wires many times as I modified other aspects of the car. I replaced the wires and put it all back together and the pump worked like a charm. I put it on my shelf so that I could have a spare if I ever needed one. Long before I ever needed a spare, a friend of mine decided he was going to modify his car on a budget. I sold him that pump, 4 years ago and it is still working perfectly to this day.

Hope this helps. I've been around the block on these things and seen lots of "failures." Never has the problem been something that was attributed to the pump itself, it's either the wiring, the relay, or the source of power.

Nathan Plemons

I used to run one too and really liked it until I learned a few things. My car makes no less power at 180 degrees than it does at 160 degrees. Studies have shown that wear dramatically increases when you run the engine too cool. The heater works better with the 180. With all of these I went ahead and put a 180 back in it and haven't looked back. I've got the fans programmed to keep it way cooler than stock, but still warm enough to reach peak efficiency.

BrianCunningham

I found from autoxing, if the thermostat opens sooner, it takes longer for it to get about 190. As soon as it get up around that temp, I can feel the performance start to go down.

Nathan Plemons

Every car is different of course. If you're constantly keeping the revs up you're gonna see different results from a car that's driven around town all day long. I'm not surprised by your results. I've dyno'd the hell out of mine and have never seen a performance drop until it's well above 200. Racing, however, is a different story. It's not like you're never getting up to temp, you're certainly not sitting at 160!

rickneworleansla

I was looking through the FSM last night. Here's the diagram.





Here's some pics of the relays on my 95. Hopefully I have everything labeled correctly.

There is an Error Here. Please Read Post 37 Below and Post #56 for Correcct Wiring!!










Thanks everyone for the help. I'm going to go back and read over all the posts I've missed as well as the FSM.

Nathan Plemons

That's exactly what you need, and that's your problem. Notice in the wiring diagram that the pink wire is common to all three relays and goes directly to the ignition switch? This should be common to all three relays somewhere, you could use an ohm meter then to figure out that you've got the right one. You connected to the blue wire, which is only hot when the PCM commands it. Move your tap and you'll be good. :cheers

This is not to be confused with the RED wires that come off of two of the relays.

BlackC6LS3

I think I used the pink wire on my car.

grinditout

short pink = no cooling fans.

rickneworleansla

Looking back at the wiring diagram it looks like I do have them labeled wrong in the pictures. The strang thing is when I was first testing for power with the accessory switch using my multimeter the blue wire I used was the only one that was getting power. I guess the PCM is cutting it off though. I thought I had tested the pink and didnt get power there. I'll go back and check again. I will follow the pink wires back and try to tap into it further up the path.

Thanks again.

rickneworleansla

dmukina

Dont know if my post will help you at all but i just finished my install on Wednesday, i saw you posted when i was getting ready to wire mine up and you were having some issues. Since i installed mine i have had no issues, and it runs great. As i looked at your pictures i was wondering what year your corvette was? i myself have a 1992 lt1.

http://forums.corvetteforum.com/show....php?t=2175205

IRAraid

Rick,
Yes, your labeling of relays #1 and #2 is reversed. Taking that into account, the following describes what's happening.
By wiring to the dark blue, as you have done, the water pump will shut off when the ECM grounds point D11. The ECM closing the contact at D11 normally causes the fans to be wired in parallel and run at full high speed (really warm engine). When this ECM switch is open (fans on low or off) you will have 12v and the water pump will run. So when the engine needs extra cooling, the water pump shuts off if wired to the dark blue control wire.
Further, do the fans switch between off and high speed only now (no low speed intermediate operation)?
As others suggested, wire the water pump relay coil to the pink wire (not the red wire) and ground. Then the water pump will operate full time with the key. However, a blown 5amp fan control fuse will kill the water pump (future trouble shooting info).
Good luck.
PS Earlier year LT1's have a different fan control relay setup.