Jump to content

Losing Water. Stumped.


Recommended Posts

I have been losing water randomly. Everything will be fine, the temp guage always hovers around half way. Then randomly it'll spike to 3/4's (never reaching H), then I know I've lost water. I saw what I thought was water from the overflow so I replaced the cap hoping that it just wasn't holding the pressure but that didn't help. I've put new hoses and changed the thermostat. The head seems fine. The oil is super clean with no evidence of water in the head.


The distance doesn't matter either, I can drive for an hour or 15 minutes and be fine.


Any ideas?



Link to comment
  • Replies 20
  • Created
  • Last Reply

Top Posters In This Topic

Top Posters In This Topic

Yes pressure test... But, How much are you losing? also, 521s dont have overflow tanks. Usually, you get hot and pressure is released. But when cooling down it sucks coolent back in when an overflow tank is used..


Also, ive had a leak at a hose but with the motor running it would blow the droplet away. Was confused, I found my leak accidently by leaning on the hose and feeling water on the bottom... GL.

Link to comment

You may have a bad head gasket. Compression leaks into the cooling system and exceeds the 14 PSI rad cap and vents coolant while driving. You may not even see any wetness. Put the over flow pipe in a bottle and keep track of how much comes out. If it equals what is missing from the rad this is where it's going. It's normal to spit out a teaspoon every now and then.


This is not a fix ... but you can get a (special) rad cap from a newer vehicle with coolant recovery. Just stick the over flow hose in a container half full of coolant so it is submerged. Anything vented when warm is siphoned back in when the motor cools. I have this on all my older L series motors. Rad never goes down. The original rad cap won't work for this.

Link to comment

If your loosing water threw a piston(bad headgasket), then that spark plug will be a different color than the rest of them, but generally when that type of headgasket failure happens, it pressurizes the radiator and blows the water out when you take the cap off, it doesn't necessarily get water in the oil though.

I can say this with certainty, if you are pumping water threw a cylinder slowly, quit driving it and fix it, because it can turn into a big issue very fast. 

Link to comment

Thanks, all!


I'll check the plugs tomorrow. I put the overflow hose in a coke can and it's about half full and I barely noticed any water leakage. Once I pull the plugs and make sure there's no water in the cylinders I'll take it to a rad shop and have them pressure test it.


You guys are awesome, thanks for this.

Link to comment

Let me jump ahead slightly here. IF you decide to change the head gasket yourself or have a friend do it, be sure you know how to block the timing chain tensioner so it does not fall out when the cam sprocket is removed. It's a simple and easy thing to prevent and a half day (often more) of extra work and expense if you don't.


Not saying you can't change the gasket yourself, you most certainly can, I've done it 4 or 5 times at least. It's easy enough and cheaper. The last one I did cost me $23 for the gasket. Just find out how to block the tensioner.

Link to comment


The plugs seem to be OK. I just bought the car about two months ago and was told that there was a tune up done about a year ago. The second cylinder had an Autolite plug and the rest had champion (which is weird) but they all look to be in relatively good condition so luckily it looks as if no water got into the cylinders. Also, now that I added a bottle at the end of the overflow hose I've barely lost any water at all.

Link to comment

I don't think that's my truck, mine was originally green. The flat green blends well. No carpet and stock horn so I'm not sure it's Kyle's either.


I was reading in other posts about motor oils and it's looking like a high mileage 30W is the way to go for Seattle's climate.

Link to comment

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

  • Create New...

Important Information

By using this site, you agree to our Terms of Use.