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Coolant leak, from heater?


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So driving my car and my clutch went to the floor. Ohh well ill just rebleed the clutch. I got home parked my car and realized I was leaking coolant, but not just a little.



And then i looked under the car and saw coolant leaking. Popped the trunk and saw coolant leaking from the heater valve on the passenger side,




And it's leaking from here also.


I'm guessing a bad heater valve, or heater core? Any buddy else have a guess? I was talking to Casey and he said I should probably bypass the heater untill I can find a new one or rebuild it. I might do that to see if it stops leaking. But besides that the car runs beautifully!'

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Inspect all your rubber hoses and connections .. could be something as stupid/simple as that (hopefully) especially if it's old stuff ( as you know ).


Bypass if you don't have the funds/time/is a daily driver , and replace if you do have the funds (and time..) to install. (get a second hand to help if you've never done before).

Heater-core replacement CAN turn into a big job if you haven't done one before as well.

Heater-cores go bad often.. or just plug up ..

what also happens is people "tug" on the connections at the firewall and sometimes disturb the joint(s) UN-intentionally.


Sure heater-valves go bad , and need to be replaced or re-built/resealed typically.


If you're planning to drive during winter I would suggest fixing while it's nice out.

I don't care it being 33 degrees in my car when driving , but I do care whether I need a defroster or not... that usually requires heat :lol:

I'd replace all the rubber leading to and from the heater-core , so it doesn't have to be looked at in the future as well.

BUT... I have no idea how much of a task a heater-core is in a 510 (if you can get by without having to pull the dash..)

In s30's it's like every other stinking car ... where the dash has to come out .. do'h


Word to the wise ...

heater-cores "can" leak straight out of the box.

I try to test mine before installing , so effort isn't wasted.

This not always , but it "can" happen.


For future info some radiator shops are willing to repair them , and it's a good option if you ever can't get ahold of new or good one because it's a rare car or becoming one (like my brothers ride...)


Good luck.


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bypass is the right decision for the moment even if you replace it in 2-weeks.


I'd bypass it as soon as possible.. drive another car to get some hose or get a ride !

Depending on how bad that leaks (looks like a sizeable amount) I'd stop driving it.

Some heater cores leak a little , and others leak a lot. (hard to know without seeing it).

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I wouldnt just keep topping it off. That kind of move is normally reserved for someone whos already on the road and just needs to make it home or something similar. Would be a little irresponsible to ignore a known problem like that, that could ruin all the hard swap work you just did. Overheating and warped heads are no joke. 



Just bypass the core until you can fix the valve or whatever is leaking. 

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Already bypassed the heater. Problem fixed. But I realized my cluth slave cylinder was leaking from the piston and seal. So my new question is will a 240z clutch slave cylinder work on a 510. Both of the forks have a hole for the rod to push through.

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Ill probably bypass it for now. Time toget a bigger hose. Could I hurt the car driving with the leak? If I keep topping it off?


You run the risk any time the coolant leaks. Top it up?... right and you soon get complacent with that. Why TF did it boil over and warp the head????? I drove it all day yesterday without topping it up!!! This isn't fair!!!


By pass for now. ... and it isn't a larger hose... it's a LONGER hose.


I also have a slave clyinder leak from the chamber the rod sits in. Will a 240z slave cylinder work on a 510?


I'm guessing this is not a 510 but an A10? People need to know these things when describing a problem... just like a doctor. Yes the 240z slave should work well enough. Use your push rod.




Those heater hoses look new. Bet you pulled the old ones off and cracked the solder joints. When replacing an old hose use a box cutter to slit the rubber so it comes off without pulling on it.

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