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Hello! I love this 2004 c5 manual vette I picked up a couple months ago. I have installed the corsa sport exhaust and z06 wheels!
However, I noticed a few drops of coolant on the pavement soon after getting it. I replaced the thermostat/housing (duralast) and radiator drain plug (acdelco). Now its leaking A LOT more than a 5 drops. I'm 60% sure that a bead of silicone on the housing mating surface would fix it? Many on here said to not use a gasket or sealant, that the thermostat's rubber seal is what seals it. Your thoughts? Thanks in advance!!
Two possible leaks are water pump t-state housing or there is a weep hole under the pump neck. Starts slow then gets worst. Its telling you better change me. When you park car is there a little fluid in center or close to it engine?? JMG
Last edited by Vetteman Jack; Oct 20, 2024 at 12:04 AM.
so could be the water pump? it looks dry over there. first pic u can see that the coolant is almost directly under the crank pulley , center of engine bay. However I can really only see coolant dripping from the thermostat housing.. I did wipe both surfaces with break cleaner before tightening the bolts when installing. Also I made sure the thermostat seal key was correct in rotation in the housing.
Last edited by Vetteman Jack; Oct 20, 2024 at 12:05 AM.
I am sure that you double checked, but there was a water pump and thermostat housing casting change somewhere in the C5 production.
The Rock-Auto site warns you to be sure you are buying the correct thermostat housing for the water pump casting.
thank you all for your responses! I appreciate it.
it's looking like I'll need to replace the water pump... which I haven't done in over a decade. I can either do it myself now or wait to pay a shop because funds are tight. this is a real bummer but at least it won't be too expensive.
after looking at the diagram again, the puddle is right below the water pump!
It looks like the thermostat housing is wet. You have to know what you have for a pump. Early pumps used a one piece thermostat/housing with a standard gasket, and the 2004 uses a thermostat with a rubber seal around the perimiter to seal. The aftermarket now sells one that fits all, and comes with both gaskets (rubber and standard). If memory serves me correctly, the earlier one has a larger hole and if using just the rubber seal of the later one, you will have a leak. I remember one of the combinations requiring using the rubber seal and the gasket - it was really hokey. You had to have the one piece t-stat and housing for the earlier pumps and the 2004 housing for the 2004. I returned that fits all pump and bough the one specific to the 2004. I have the old water pump in the shed and could measure the hole size for you if need be.
Replace pump. Replace thermostat. All new gaskets. Problem solved.... Because if you have to drain the coolant you may as well do it all while you're in there. For that matter, fresh hub if not already done too?
It looks like the thermostat housing is wet. You have to know what you have for a pump. Early pumps used a one piece thermostat/housing with a standard gasket, and the 2004 uses a thermostat with a rubber seal around the perimiter to seal. The aftermarket now sells one that fits all, and comes with both gaskets (rubber and standard). If memory serves me correctly, the earlier one has a larger hole and if using just the rubber seal of the later one, you will have a leak. I remember one of the combinations requiring using the rubber seal and the gasket - it was really hokey. You had to have the one piece t-stat and housing for the earlier pumps and the 2004 housing for the 2004. I returned that fits all pump and bough the one specific to the 2004. I have the old water pump in the shed and could measure the hole size for you if need be.
thank you for the info! the thermostat I installed has the rubber seal, shown below.
Originally Posted by Tusc
Replace pump. Replace thermostat. All new gaskets. Problem solved.... Because if you have to drain the coolant you may as well do it all while you're in there. For that matter, fresh hub if not already done too?
agreed, im going to have to drain all the coolant again and replace the water pump, I was just being wishful since I saw coolant dripping dirctly off of the thermostat housing at first. However I'm not sure why it went from a 5 drips to a puddle. I did install new a/c and accessory serpentine belts since they were cracking. replacing the water pump on jack stands (on a creeper) will be very tough, I may just save up and take it to a shop.
is hub the harmonic balancer? I'll want to replace that, too!
thank you all for your responses! I appreciate it.
it's looking like I'll need to replace the water pump... which I haven't done in over a decade. I can either do it myself now or wait to pay a shop because funds are tight. this is a real bummer but at least it won't be too expensive.
after looking at the diagram again, the puddle is right below the water pump!
Don't freak out it's not going to blow up or anything. Just kept an eye on it and you can still drive it. I drove mine for months to get up the ambition to tackle it, As it gets worse all that happens is more drips under car. Keep an eye on anti fr level that all.
Don't freak out it's not going to blow up or anything. Just kept an eye on it and you can still drive it. I drove mine for months to get up the ambition to tackle it, As it gets worse all that happens is more drips under car. Keep an eye on anti fr level that all.
true.. I could have before I changed the housing since it was only about 5 drips, but for some reason now its the puddle u see in pic #1. I may just have to tuck it away for winter ):
ps. I went to test drive the car 2 hours away and it was raining moderately, i didnt even think to check for a fluid leak until after the drive. could've stopped at a gas station canopy. oh well I would've still bought it! its nice having a v8 again.
thank you all for your responses! I appreciate it.
it's looking like I'll need to replace the water pump... which I haven't done in over a decade. I can either do it myself now or wait to pay a shop because funds are tight. this is a real bummer but at least it won't be too expensive.
after looking at the diagram again, the puddle is right below the water pump!
The water pumps on these C5s are super easy to replace, easiest water pump I have ever done on any vehicle. While you have the coolant drained and the water pump off, take a look at the condition of all your hoses, if they look bad and they are super soft replace them at the same time.
The water pumps on these C5s are super easy to replace, easiest water pump I have ever done on any vehicle. While you have the coolant drained and the water pump off, take a look at the condition of all your hoses, if they look bad and they are super soft replace them at the same time.
thank you for the assurance and motivation! online says its a 2-3 hour job (which will probably take me double that) where I've replaced about 20 water pumps years ago. Sounds straightforward. I ordered the correct 2004 water pump from rockauto, GM GENUINE 251744, probably doing it this weekend!
I looked up the harmonic balancer replacement... and with having to drop the steering rack, starter, exhaust, radiator, etc... I'll need to pay a shop for that.
thank you for the assurance and motivation! online says its a 2-3 hour job (which will probably take me double that) where I've replaced about 20 water pumps years ago. Sounds straightforward. I ordered the correct 2004 water pump from rockauto, GM GENUINE 251744, probably doing it this weekend!
That is the best pump. Make sure you have the appropriate 2-piece thermostat/housing for that pump. I would also order 4 mount bolts as well, they are often corroded. If you cant find GM, ARP makes a nice replacement.....
That is the best pump. Make sure you have the appropriate 2-piece thermostat/housing for that pump. I would also order 4 mount bolts as well, they are often corroded. If you cant find GM, ARP makes a nice replacement.....
thank you! yes I have the duralast 2 piece thermostat and housing that fits the 2004. I would have ordered oem but I wanted to go pick it up that day.
two better shots taken last night, going to be replacing this weekend since the new waterpump will be here tomorrow!
I do not see where a pressure test was performed to confirm the diagnosis. You might get lucky with the parts change, but why not be sure?
I don't have a pressure tester... and the coolant is dripping directly from the underside of the waterpump. You think this is a shot in the dark after those pics?
I don't have a pressure tester... and the coolant is dripping directly from the underside of the waterpump. You think this is a shot in the dark after those pics?
Most people do not have a pressure tester, that's why all major auto parts stores rent them. For coolant I use a pressure tester, for oil I use dye. Fluids travel in weird ways.
Your money, your time, your car.
Chasing a Coolant Leak (pics)
