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Fix waterpump leak

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Old Jun 19, 2026 | 10:49 AM
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Default Fix waterpump leak

Hey Guys,
I started my car for the First time since march today, wanted to do a Testride after renewing my Suspension and it seems Like a new Problem came Up. My waterpump is leaking from the Driver Side passage. After running for 5 Seconds it Sprays water in the Air. Changed oil recently and there was no water in it.
Is there a way to Just unbolt it with everything still attatched( belts, maybe even Fan) , Put a new Seal in it with silicone and bolt it Back on? Also does anybody know the exact sizes of the Bolts?


Have a nice day
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Old Jun 19, 2026 | 11:21 AM
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Just to give you an idea, this is generally considered a pretty basic repair, assuming there isn’t another issue that caused the leak.

The cooling system is a relatively low-pressure system. If you haven’t experienced any overheating or other condition that could have created excessive pressure, then what you’re likely looking at is a failed gasket or a previous installation issue.

This would be a great opportunity to learn. The water pump is essentially a bolt-on component. I’d go old school—pick up a repair manual and follow the procedures step by step.

Take pictures as you disassemble it, keep track of bolt locations, clean the gasket surfaces thoroughly, and you’ll learn a lot in the process. These older small-block Chevrolets are about as straightforward as they come.
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Old Jun 19, 2026 | 11:21 AM
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What you are asking is called "slip and slide" in the automotive trade. A common practice used by mechanics being paid flat rate for warranty repairs. I use to do head gaskets on Chrysler 2.2/2.5 engines like that. The down side is that you can't really clean the gasket surface. Do once, do it right, take the pump off. It's your car.
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Old Jun 19, 2026 | 11:24 AM
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Are you positive it's the joint between the pump and block and not a tiny crack in the pump itself? If the joint, have you tried snugging the mounting bolts a bit more?

I'd think your plan is doable, but probably not going to be very successful. The two gasket surfaces need to be scraped clean of all old material/sealant. In the process you're also going to have to loosen the other side to pivot out the leak side enough which then necessitates replacing that gasket too.

Bite the bullet, remove the fan, belts, and pulley. Pull the various hoses from the pump and unbolt it – I believe they're 9/16" bolts.
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Old Jun 19, 2026 | 11:52 AM
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Okay you convinced me to do it right. My Problem is, i expect to have a Problem to get the heater hoses Off of the water pump without destroying them. But i might even be able to keep them on, i'll Figure it Out while doing the Work.
One bolt is Missing on the Side thats Not leaking. Does anyone know the size? That would be awesome.
And to get IT sealed you Clean it good, tack the Seal in with some RTV on both Sides and then Torque it to spec after letting it dry for some time right?
Oh and edit: im pretty Sure its the Seal itself. I checked IT and a piece of IT hängst Out, another piece ist Missing. It Looks Like someone did that Job before and Just used black silicone.

Last edited by 777max; Jun 19, 2026 at 11:55 AM.
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Old Jun 19, 2026 | 12:46 PM
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I would just cut the old hoses off with a razor blade and replace them. The bolts are 3/8x16. The length is probably the water pump plus any accessory brackets and add a 1/2 to 5/8 of an inch for the length. I don't use sealant on the gaskets. Just clean and dry. I do however use loctite 565 on the bolt threads being the bolt holes are "wet". Go nice and slow with the water pump bolts. They can break.
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Old Jun 19, 2026 | 01:30 PM
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Originally Posted by Fly skids up!
I would just cut the old hoses off with a razor blade and replace them. The bolts are 3/8x16. The length is probably the water pump plus any accessory brackets and add a 1/2 to 5/8 of an inch for the length.
Depending on how old the hoses are and whether new ones are warranted: to keep the current hoses, you could slit the hose on the fitting about 1" (2.5cm) to remove it and then cut off the sliced section. You're only losing ~1" of length doing this which shouldn't affect much.

The 9/16" I mentioned above is the hex head. Look at the pump mounting ears on the side missing the bolt. If both ears are the same thickness and no bracket on one vs. the other, just duplicate that length.
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Old Jun 19, 2026 | 02:11 PM
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To remove a hose, heat the area where it contacts the fitting. Use a heat gun or hair dryer. Twist on the hose several inches up from where it contacts the fitting. That will almost always allow you to get it off without damaging the hose.
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Old Jun 19, 2026 | 03:52 PM
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remove the fan & fan clutch from car.
remove the pump from the car.
Place pump on bench and clean both R&L sides' pump gasket surfaces and both blocks' gasket surfaces. And replace both R&L gaskets.
Use a thin skim coat of Permatex #2 non-hardening and also coat all 4 bolts' threads with same. It's old-fashioned and works like a champ.
Suggest replace Both hoses with new and New hose clamps.
Do it right and it won't return to haunt ya.

* if the pump itself is leaking from its main-shaft front seal OR from its rear backing plate, you should replace it with either a new or a rebuilt pump.

Last edited by Rebelyell; Jun 19, 2026 at 03:59 PM.
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Old Jun 19, 2026 | 08:48 PM
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The "bubba" way to fix it would be to add some radiator stop leak and hope for the best. Might work might not.
A said above remove and fix properly.
IMO new water pump, gaskets and coolant hoses all around.
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Old Jun 19, 2026 | 11:31 PM
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I have a waterpump sitting on my work bench. If you can post up a picture of the missing bolt and any other mounts that may be in the same location. I can give you a bolt size.
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Old Jun 20, 2026 | 03:01 AM
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Im currently Not at the Car but the Bolt thats Missing ist the one, that also holds the ac compressor bracket in place.
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Old Jun 20, 2026 | 03:25 AM
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3/8th's 18 × 2 1/2 is the lower left. The upper left I believe is the one with the bracket. It's been a few years since I ran a factory compressor, but if I'm correct that one would be 3/8th's 18× 2 inch.
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Old Jun 20, 2026 | 05:15 AM
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Thanks for the reply. Are you Sure theyre 3/8-18? Can only find 3/8-16 online.
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Old Jun 20, 2026 | 06:03 AM
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I think your right. Should be 16 pitch. My mistake.
go with a grade 5 bolt and flat washer.

Last edited by 4-vettes; Jun 20, 2026 at 06:04 AM.
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Old Jun 20, 2026 | 07:24 AM
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Thanks a lot for the Help. Ordered the Seal, new hoses, new screws and coolant and will fix it properly.
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Old Yesterday | 05:57 PM
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Some things to consider: 1. for hoses, use a cotter pin puller and slip between hose and metal nipple. While puller is in that position spray BRAKE CLEANER between hose and nipple that the cotter pin puller has opened up, then twist hose on the nipple to loosen. Try more sprays if needed.

2. The broken bolt is probably rusted to pump. Be careful when trying to remove the pump. Use Kroil to spray into area of broken bolt. Gently rotate pump around broken bolt to see if bolt is free of the pump. Spray again, pull straight off while gently rotating pump back and forth.

3. Run a thread chaser or tap into the threads in the block and clean out the debris.

4. Replace all bolts and apply a THIN coat of Teflon paste on the bolt threads.

5. Clean gasket surfaces on the block and water pump. If you want to apply sealer on the gasket surfaces, use Permatex #22071 Gasket Maker due to its high resistance to water-glycol fluids.

Just my opinion.

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To Fix waterpump leak

Old Yesterday | 08:07 PM
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When you start getting into the work and time involved, keep asking yourself this one question, how soon do I want to go through all or any of this work again.
That water pump looks like it’s been on the engine for a while.
While you’ve got it off, consider replacing the pump.
A good replacement pump isn’t expensive and well worth the headache of doing the work again if the pump decides to start leaking this season or next.
Once you remove everything you might decide to install a new pump, fan clutch, belts and hoses.
If you replace the lower radiator hose, make sure the new hose includes the internal spring.
You have to remove them all anyway.
You’ll see why I make the suggestion when you do get it all apart.
Just my $.02 worth.

Last edited by OldCarBum; Yesterday at 08:09 PM.
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Old Yesterday | 08:28 PM
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This was the bolt layout on our '72. Also, you mention that it appears a gasket is hanging out a bit. The same gasket is used on both side of the pump, but one leg of the pump is shorter that the other, and unless the gasket is trimmed, it will appear to hang out. Could that be the case with you?


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Old Yesterday | 11:37 PM
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Looks like your bolts are intact, and I see no need to replace them. Just clean the threads with a wire brush. I usually trim the gasket for the right side just to make it look better, cosmetically. The primary issues with aging water pumps are the shaft bearings, vanes rusting off the shaft, or the vane assembly spinning on the shaft either of which will cause water flow to stop. I also like to add one or two bottles of Water Wetter to the cooling system during refill which helps with heat transfer. (jmo)..
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