Signs of water pump failure? (S13 KA24DE)

[Agent_S13]

So I replaced the radiator a few months back after noticing a small leak in the original OEM plastic radiator. I didn't replace anything else at the time.

Today, noticed a pool of coolant on the floor.

Turned car on to see when thermostat would open. Techtom indicates at least 200 (F) before what sounds like the thermostat opens and when it does, it starts spraying coolant in the engine bay.

I thought it was the hoses, replaced both (upper/lower) but still having issues.

Since its hitting the electric/clutch fans where could this (pressurized) leak be coming from?

Is it as simplistic as replacing the water pump/thermostat?

Is it safe to re-use the thermostat housing or just safer to pick one up (if I can)?

Obviously I want to get this taken care of ASAP so any information anyone can provide would be appreciated:

TLDR:
Replaced radiator (w/ aluminum model)
Replaced radiator hoses (w/ silicone versions)

Still leaking, replace water pump/thermostat and hope that's the end of it? It is spraying coolant on the fans which isn't help me track down where its leaking directly since its going everywhere but hoping its just a failing water pump and a leaky gasket.


If anyone can offer a suggestion of where I may be spraying coolant and what else I should replace, please let me know. Will be spending tomorrow sourcing parts and seeing if I can schedule time w/ my mechanic on Friday. Figure this should only take a few hours -- no need to replace anything else.

Thanks in advance!

-Aaron
'91 240sx coupe

[sidedrifts13]

did you bleed the coolant system properly? what temp thermostat did you get? bleed the coolant system and use some good silicone/ gasket sealer, was your cooling system running pure water before? sometimes the return line can get clogged, just take your time dont get frustrated and re seal the water pump and make sure everything is nice and clean before you install it

[BKangS14]

a bad waterpump would be when your car is at idle and starts to overheat but if you give it gas and it cools it down thats because the waterpump is stuck or seized up and wont let coolent go through so when you give it gas the pump would spin to let the coolent pass by.

[Agent_S13]

Thanks for the prompt replies.

did you bleed the coolant system properly? what temp thermostat did you get? bleed the coolant system and use some good silicone/ gasket sealer, was your cooling system running pure water before? sometimes the return line can get clogged, just take your time dont get frustrated and re seal the water pump and make sure everything is nice and clean before you install it

I doubt it. I had the cap off and the bleeder screw open. When it got warmer (watching the techtom, which isn't the most accurate place to get the temp, hit 200 and then a "whoosh" sound) I figured the thermostat opened, but its OEM so it should open at 170 (F). Nothing ever came out of the bleeder screw -- always bubbling out of the radiator.

That's when I got the spraying everywhere. More or less, something was leaking, it was hitting the fans which sprayed it everywhere. Hard to source the leak when its doing that.

Was running a mix of coolant/distilled water (close to 50/50 as possible). Also when I removed the hoses -- coolant will still fine, no rust.

I'm buying a new thermostat (Duralast - 170 F) and waterpump today though. Figure mechanic can install, test and see if I missed anything -- really hoping its related to a failing/poorly sealed pump.

a bad waterpump would be when your car is at idle and starts to overheat but if you give it gas and it cools it down thats because the waterpump is stuck or seized up and wont let coolent go through so when you give it gas the pump would spin to let the coolent pass by.

Well I was letting it idle, while hoping to bleed the system. Nothing came out of the bleeder screw, everything was popping out of the radiator instead along with that random leak.

I drove it around the block since its a slow buildup of heat --- techtom continues to rise in temp (up to 225 F) but also noticed that there was a leak near the thermostat housing. Clamp/hose seem pretty good -- figure I'll try to source a new housing since it seems thin/prone to cracking.

If anyone has anything else to offer, please keep it coming.

Are the new Mishimoto radiator's prone to failing/leaking? I didn't see anything negative before buying it a few months back.

-Aaron
'91 240sx coupe

[murda-c]

You could get a pressure tester for the radiator.

[Agent_S13]

You could get a pressure tester for the radiator.

I'm seriously hoping that's not the case as the water pump seems to be OEM/original on a 19+ year old car and more liable to fail than a 6 month old radiator.

I've already got my parts ordered (thermostat/water pump) and I figure it'll be up to the mechanic's hands to figure out if I have something else failing in the cooling system (pray's its not the radiator as that's a special order part and wait time sucks). :rl:

Any input on re-using the thermostat housing? If its off/uneven, could it be sanded smooth again (if its not cracked?)

Thanks!

-Aaron
'91 240sx coupe

[bl3ujay07]

a bad waterpump would be when your car is at idle and starts to overheat but if you give it gas and it cools it down thats because the waterpump is stuck or seized up and wont let coolent go through so when you give it gas the pump would spin to let the coolent pass by.

not necessarily. There are other symptoms like leakd from weeping hole. OP, if you suspect that it can be the water pump, why not just take out the fan and start it up to see if it is water pump or not.

[bl3ujay07]

I'm seriously hoping that's not the case as the water pump seems to be OEM/original on a 19+ year old car and more liable to fail than a 6 month old radiator.

I've already got my parts ordered (thermostat/water pump) and I figure it'll be up to the mechanic's hands to figure out if I have something else failing in the cooling system (pray's its not the radiator as that's a special order part and wait time sucks). :rl:

Any input on re-using the thermostat housing? If its off/uneven, could it be sanded smooth again (if its not cracked?)

Thanks!

-Aaron
'91 240sx coupe

Just clean the surface and then use liquid gasket. It should be fine.

My advice, no need to take it to a shop. Its not hard at all doing water pump compared to fwd cars. Take off clutch fan and fan shroud if you have one, and you have access to the water pump. Save yourself some money.

[didderson]

Easiest way to test water pump is check the weep hole.
If the bearing seal fails coolant seeps through the weep hole, you'll find it if you look on the cast housing behind the pulley mount.
If it's wet, time to change it soon.

Otherwise it should work fine internally and mechanically until you die (for a long ass time), but the bearings and seals fail.

Unless something harmed it like a big rock running thru your coolant or it was installed wrong.

[Mangudai]

Easiest way to test water pump is check the weep hole.
If the bearing seal fails coolant seeps through the weep hole, you'll find it if you look on the cast housing behind the pulley mount.
If it's wet, time to change it soon.

Otherwise it should work fine internally and mechanically until you die (for a long ass time), but the bearings and seals fail.

Unless something harmed it like a big rock running thru your coolant or it was installed wrong.

Is this weephole in the same location on the S14? It's my first hearing of it.

[Agent_S13]

Just clean the surface and then use liquid gasket. It should be fine.

My advice, no need to take it to a shop. Its not hard at all doing water pump compared to fwd cars. Take off clutch fan and fan shroud if you have one, and you have access to the water pump. Save yourself some money.

Thanks. I had the shroud removed when I installed the larger radiator so I can see/access both fans. Its just that I don't have many of the tools and I figure I can leave the car with the mechanic while I go to work. I wanted to replace all this stuff anyways and I don't trust my own work to get it done.

Easiest way to test water pump is check the weep hole.
If the bearing seal fails coolant seeps through the weep hole, you'll find it if you look on the cast housing behind the pulley mount.
If it's wet, time to change it soon.

Otherwise it should work fine internally and mechanically until you die (for a long ass time), but the bearings and seals fail.

Unless something harmed it like a big rock running thru your coolant or it was installed wrong.

Sadly I have coolant everywhere, so everything's wet. =(
I believe its original and 160k miles sounds right about a water pump finally giving out. Might as well replace it.

I do think the weephole is a "sign" that the pump is on its last legs. I'm just hoping that's where the leak is coming from and no some weird place (return line, radiator itself, etc) and that I can have the car up/running quickly -- my only car.

I may even request to remove the upper timing chain guide since I hear it rattling away too under the valve cover.

Thanks to all of the replies, I haven't been back on this board much (house upgrades > car upgrades) but its great to see the quick/response replies of the community.

-Aaron
'91 240sx

[shinobis13hb]

same problem i had 2 years ago just replace the water pump. its not much money and its always great knowing you have a new good working part on your car. jsut make sure you get the gasket for the water pump and use some permatex gasket maker, bleed the system properly i ushally let the thermostat open about 3 times and im good from there any other air bubbles will wokr them selfs out.

[Agent_S13]

same problem i had 2 years ago just replace the water pump. its not much money and its always great knowing you have a new good working part on your car. jsut make sure you get the gasket for the water pump and use some permatex gasket maker, bleed the system properly i ushally let the thermostat open about 3 times and im good from there any other air bubbles will wokr them selfs out.

Thank you, sir.

I figured its time to replace 'em anyways. I ordered the new gasket with it [along w/ a new thermostat, gasket and will see about a new thermostat housing since it seems to be leaking and I already have the new silicone hoses in place (bad clamps?)] and figure some additional permatex will help make sure things are running/fine and keeping engine temps cool.

I also ordered a new sensor just to be safe -- I still don't trust the techtom and figure that could be an issue of why things are running so oddly (techtom indicates my running temps between 165 - 175, with 180 on hot days).

Here's hoping to get my 240 back on the road. Or would it be too much to see about finding an SR... naw, not in California. :rolleyes:

-Aaron
'91 240sx coupe

[jumboflan]

Thank you, sir.

I figured its time to replace 'em anyways. I ordered the new gasket with it [along w/ a new thermostat, gasket and will see about a new thermostat housing since it seems to be leaking and I already have the new silicone hoses in place (bad clamps?)] and figure some additional permatex will help make sure things are running/fine and keeping engine temps cool.

I also ordered a new sensor just to be safe -- I still don't trust the techtom and figure that could be an issue of why things are running so oddly (techtom indicates my running temps between 165 - 175, with 180 on hot days).

Here's hoping to get my 240 back on the road. Or would it be too much to see about finding an SR... naw, not in California. :rolleyes:

-Aaron
'91 240sx coupe
yeah you need to replace that aging water pump. It's really cheap rebuilt. Or non OEM ones. It's really easy to change. I had that problem too like 5 years ago. Coolant was under my engine and everywhere. it's hitting the fan and splashing when leaking through the bad internal seal of teh waterpump.

I bet you'll have a fun time changing it. It's a breeze. Just use enough sealant when putting it back.

[Agent_S13]

yeah you need to replace that aging water pump. It's really cheap rebuilt. Or non OEM ones. It's really easy to change. I had that problem too like 5 years ago. Coolant was under my engine and everywhere. it's hitting the fan and splashing when leaking through the bad internal seal of teh waterpump.

I bet you'll have a fun time changing it. It's a breeze. Just use enough sealant when putting it back.

Thanks. Picked up a new Duralast one (new) along with a new thermostat. While it could go quick, I'm slow and figure in the time it takes the mechanic to fix it, I could earn more money...

I'm having it pressure tested tomorrow just to be sure, but hoping that and re-installing the lower radiator hose to the thermostat housing (I see some leakage) will do the trick.

I noticed another symptom - temperature only rises while driving, stabilizes while idling but if I idle too long -- will rise again. Only way to cool it completely -- shut off the car.

Guessing its just too much air in the system. I just want to get this fixed ASAP.

-Aaron
'91 240sx coupe

[Agent_S13]

So for those who were interested in a resolution:

Water pump seal is gone (its the original piece), no other leaking in the sytem! At least I'll get this take care of quickly.

Unfortunately, I learned the car is leaking oil near the oil pressure switch and the oil pan.

Meh, get it all done so I can go back to enjoying this car. I just hope that's the last of it for now. :doh:

Thanks all who chimed in. The information pretty much confirmed the diagnosis.

-Aaron
'91 240sx coupe

[stinky_180]

The water pump will start leaking once it has failed.

[OneSicSilvia]

Ya, mine decided to just start dumping coolant when it went. Alot of times you can tell if the pumps getting bad by takin the belt off and wiggling the wheel left and right ( like quarter spins). If you hear and slight grinding it's gone. if the wheel seems to have slack in it. It's probbably time for a new one soon.