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Burnt coolant smell - Bad radiator cap?

shadowless127

Explorer Addict
Joined
December 13, 2007
Messages
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City, State
Long Island, NY
Year, Model & Trim Level
'01 EB AWD 5.0
So I was driving this afternoon and had to romp on it pretty good to attempt to avoid an accident. Afterwards as we're driving me and my gf notice a sweet smell. I assumed it was burnt coolant. As we continued to drive, the smell died down. Got to our destination and the smell was extremely faint. Drove home ~20miles on the highway, no problem. I just went out to grab some dinner, and I get home and smell the burnt coolant smell again, pretty strong (its only a half mile to where I went and back. Smell is coming strongest from the radiator area. Popped the hood and can sell it, strongest up front. Look in the overflow and there's no oil in the overflow, checked the oil cap and dip stick, oil is in good shape. No smoke or coolant smell from the exhaust (a bit of moisture dripping, but it doesn't appear to be coolant). Temperature is fine, car runs like usual.

I let it sit for about 20minutes, turned it back on with the hood open and didn't smell as bad. Put the hood down, romped it up the street, came back, I can smell it again, pop the hood no visible leaking, oil and overflow in good order and no smoke from the exhaust.

Could this be a bad radiator cap? The radiator, tstat & housing, and water pump were all replaced in February. They for some reason, didn't bother giving me a new radiator cap.
 



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You should be able to see where it's leaking antifreeze. Check the intake manifold, in the front is where mine leaked but can leak in the back of it also. Check around headgaskets. See if anything is dripping off from radiator. Check around all the hoses and connections
 






You should be able to see where it's leaking antifreeze. Check the intake manifold, in the front is where mine leaked but can leak in the back of it also. Check around headgaskets. See if anything is dripping off from radiator. Check around all the hoses and connections

I have a 5.0 not the 4.0.

I don't see anything dripping on to the ground from the radiator, but as I said the smell in strongest from the front of the engine bay. The further towards the firewall you go, the less the smell is.

I drove 20 miles home after the initial smell started and did 60-65 almost the entire way and when I got home I didn't notice the strong smell. But after driving to the pizza place, turning the car off, coming home from the pizza place, turning car off, I noticed the smell.

If it was leaking from a head gasket wouldn't I notice white smoke and sweet smell from the exhaust as well as discolored oil or discolored coolant in the overflow? My only other guess is a pin hole leak that only leaks under high RPMs and shoots it directly onto something hot in the engine bay. If I let the car idle there's no smell.

I'm praying it's not a head gasket, I simply cannot afford to deal with that problem this month.
 






I would check the firewall...

For leakage at the heater control valve/ hoses to it...The last time I had a coolant smell it was coming from the heater control valve hoses that had a minor split in one of the hoses...

I planned to replace the hoses and the valve and the truck decided it wanted attention NOW and blew the hose and the control valve at the same time...I had coolant under pressure spraying out of both onto the firewall and at least I got home so I wasn't stranded...

I smelled it but didn't notice the leak until it got bad enough to leave a small puddle under the truck and I thought it was the drain from the evaporator I was seeing....
 






I recall that you've spent a fair amount of money on your cooling system this year. You might want to try this product... it's called K-Seal. I had 2 pretty good leaks last winter in 2 of my 5.0's (I'm talking constant drips/puddles). I believe one was a water pump and the other the timing cover leak. I planned to fix both, but someone turned me on to this stuff. It is nothing short of amazing. no snake-oil here. 8 ounces will run you about $15-$16 bucks, but it's worth every penny. Neither vehicle has leaked a single drop since I put it in. It's a permanent fix and it remains in the cooling system to fix future leaks. one vehicle later blew a bypass hose and lost 1/2 it's coolant. I though I might have to add more K-Seal, but it wasn't necessary. If you've got a small leak somewhere this stuff will fix it. it will not clog your radiator or heater core either. suck out some coolant from the rad and put it in there and not in the expansion tank for quick results. stopped both my leaks in about 15 minutes.

BTW, if you rad cap is leaking you'll see it on the back side of the rad.
 






For leakage at the heater control valve/ hoses to it...The last time I had a coolant smell it was coming from the heater control valve hoses that had a minor split in one of the hoses...

I planned to replace the hoses and the valve and the truck decided it wanted attention NOW and blew the hose and the control valve at the same time...I had coolant under pressure spraying out of both onto the firewall and at least I got home so I wasn't stranded...

I smelled it but didn't notice the leak until it got bad enough to leave a small puddle under the truck and I thought it was the drain from the evaporator I was seeing....

My HCV has been on my watch list for quite some time. Given the car is almost 15yrs old (8/00 build date) and it's spent all of it's live sans 2yrs in the Northeast, I wouldn't be surprised if a hose is leaking somewhere.

I recall that you've spent a fair amount of money on your cooling system this year. You might want to try this product... it's called K-Seal. I had 2 pretty good leaks last winter in 2 of my 5.0's (I'm talking constant drips/puddles). I believe one was a water pump and the other the timing cover leak. I planned to fix both, but someone turned me on to this stuff. It is nothing short of amazing. no snake-oil here. 8 ounces will run you about $15-$16 bucks, but it's worth every penny. Neither vehicle has leaked a single drop since I put it in. It's a permanent fix and it remains in the cooling system to fix future leaks. one vehicle later blew a bypass hose and lost 1/2 it's coolant. I though I might have to add more K-Seal, but it wasn't necessary. If you've got a small leak somewhere this stuff will fix it. it will not clog your radiator or heater core either. suck out some coolant from the rad and put it in there and not in the expansion tank for quick results. stopped both my leaks in about 15 minutes.

BTW, if you rad cap is leaking you'll see it on the back side of the rad.

I spent $700 on my cooling system in the span of 5 days in February. Everything is new sans the fan clutch which they tested and said was functioning 100%.

I will have to pick up some of that stuff. At this point with my new job my vehicle is pretty much just a station car that drives me 10 min to the train station, 10 min back, and just random errands I run locally. This upcoming week is going to be a big week only because today I drove 40miles out and back to my gf's mom's house, and Tuesday I have to drive about 60-70 miles round trip.

I see dried residue on the back of the radiator just below where the cap sits going about half way down, and seeing how it's a new radiator the leak is somewhat recent. I'll pick up a new cap for good measure anyway.
 






you should always install a new rad cap with a new rad. I think so much of K-Seal, I'm thinking of putting it in my other 3 trucks just in case any of them develop a leak in the future.
 






you should always install a new rad cap with a new rad. I think so much of K-Seal, I'm thinking of putting it in my other 3 trucks just in case any of them develop a leak in the future.

I thought they replaced the radiator cap, until upon further inspection I realized all they did was clean it up so it looked better. Just never got around to the parts store to get a new one.

This may sound stupid, but I have a good feeling about K-seal if for no other reason then the fact the packaging is VERY VERY boring and plain and looks barely thought out. Usually speaks to a good product that sells itself instead of the marketing department having to jazz up the wrapping to appear to idiots.

How much do you usually put in?
 






I thought they replaced the radiator cap, until upon further inspection I realized all they did was clean it up so it looked better. Just never got around to the parts store to get a new one.

This may sound stupid, but I have a good feeling about K-seal if for no other reason then the fact the packaging is VERY VERY boring and plain and looks barely thought out. Usually speaks to a good product that sells itself instead of the marketing department having to jazz up the wrapping to appear to idiots.

How much do you usually put in?

I put in the whole 8 ounce bottle. Putting it all in won't hurt anything. when you pour if in you'll see that it's very thin and has little crumbs of whatever in it. it reminds me of chocolate milk with cookie crumbs in it. use a turkey baster, or whatever, to suck 8 ounces of coolant out of a cold radiator before pouring in the K-Seal (shake the bottle well first) then let the engine idle (or drive it) for about 20-30 mins and that's it - done. I was amazed that it worked on my suspected water pump leak as it was pretty bad, but 6 mos later, still hasn't leaked a drop. I'm living on a fixed income and all my vehicles have over 200,000 miles on them. I feel that if I can fix minor problems with an additive that works, why not use it. I had an old 3.1 v6 Pontiac about 5 years ago. it had a coolant leak that turned out to be a bolt that went through to a water passage. I spent a day and a half tearing that motor apart to find the source of that leak, only to have to put sealant on the bolt threads. I wish I knew about K-Seal then. I would have saved myself a lot of time and aggravation.
 






If new hoses were installed a few weeks ago and they used worm drive clamps, you may need to tighten them a bit.
 






If new hoses were installed a few weeks ago and they used worm drive clamps, you may need to tighten them a bit.

I think only one of the hoses is new going to the water pump, but I can't quite get to it, and also it isn't leaking on the ground so I don't think it's that hose.

Wound up not going into the city and worked locally today so I did a bit of driving and I noticed that if I drive like a civilized human being the smell is still noticeable upon arrival, but you have to stand directly in front of the engine to smell it. I'm starting to think more and more that whatever small leak I had previously just got worse and now it's just getting coolant on hot engine parts and evaporating cause that smell. Going to go get a new rad cap and a bottle of K-Seal in about 20 minutes and we'll see tomorrow how that works out.
 






I'd tighten that hose before I added anything to the coolant. I replaced a heater hose and everything seemed fine, except for a small amount of lost coolant over a couple of months. So one day I came back from the gym, turned off the engine, popped the hood, and left the car alone for a few mins while I went inside. I came back out and started inspecting the valve covers to see if they were leaking any oil, glanced up, and saw a tiny stream of coolant spraying from the heater hose where it mates with the heater valve.

Crazy...I had done visual inspections before to look for the coolant loss with the block cold, with the engine running, and right after shutting off, and it never leaked a drop. You just had to catch it when conditions were just right for the leak to happen.

I ended up tightening the hose clamp with an 8mm socket and ratchet to get it tight enough to stop leaking.
 






I'd tighten that hose before I added anything to the coolant. I replaced a heater hose and everything seemed fine, except for a small amount of lost coolant over a couple of months. So one day I came back from the gym, turned off the engine, popped the hood, and left the car alone for a few mins while I went inside. I came back out and started inspecting the valve covers to see if they were leaking any oil, glanced up, and saw a tiny stream of coolant spraying from the heater hose where it mates with the heater valve.

Crazy...I had done visual inspections before to look for the coolant loss with the block cold, with the engine running, and right after shutting off, and it never leaked a drop. You just had to catch it when conditions were just right for the leak to happen.

I ended up tightening the hose clamp with an 8mm socket and ratchet to get it tight enough to stop leaking.

I tried visually looking for the leak but didn't see it. Tried looking for it while idling, tried looking for it right after I turned it off, tried looking for it after waiting 20 minutes, tried looking for it after sitting for 2hrs and NOTHING.

Openned radiator and 1) I don't know how the radiator cap was working at all, it was in such bad condition. 2) I think there's still some debris left in the cooling system from the old water pump; my mechanic warned me of that. Guess I will have the system flushed again when I bring it to him to inspect it and fix the AC.

Put the K-Seal in and topped off the overflow because it was about halfway between empty and the fill line. Let it idle for about 20 minutes then took a 5-6min drive and got back and the smell is substantially less. I had to really get my nose close to the grille (almost touching it) to smell it with any strength. It's still there but that could be old stuff burning off, or some of the coolant I got on the engine because I'm a butterfingers when dealing with coolant. I'm not calling it completely fixed yet, but it seems to be better.

Will update this thread tomorrow after I take my 70-80 mile trip.
 






+1 on the K-Seal. It won't fix a blown hose but definitely works wonders. I've used it in the pickup, Mustang, and Explorer-definitely simpler than changing a timing chain cover. I keep an extra bottle on hand just in case one of the Caddy's blows a radiator.

Bill
 






I tried visually looking for the leak but didn't see it. Tried looking for it while idling, tried looking for it right after I turned it off, tried looking for it after waiting 20 minutes, tried looking for it after sitting for 2hrs and NOTHING.

Openned radiator and 1) I don't know how the radiator cap was working at all, it was in such bad condition. 2) I think there's still some debris left in the cooling system from the old water pump; my mechanic warned me of that. Guess I will have the system flushed again when I bring it to him to inspect it and fix the AC.

Put the K-Seal in and topped off the overflow because it was about halfway between empty and the fill line. Let it idle for about 20 minutes then took a 5-6min drive and got back and the smell is substantially less. I had to really get my nose close to the grille (almost touching it) to smell it with any strength. It's still there but that could be old stuff burning off, or some of the coolant I got on the engine because I'm a butterfingers when dealing with coolant. I'm not calling it completely fixed yet, but it seems to be better.

Will update this thread tomorrow after I take my 70-80 mile trip.

FYI, it can take a while for the burnt antifreeze smell to go away completely. Based on my experiences with K-Seal, if you had a small leak, it's not leaking any more. You could also rinse the radiator with a hose to remove any residue antifreeze and associated smell.
 






FYI, it can take a while for the burnt antifreeze smell to go away completely. Based on my experiences with K-Seal, if you had a small leak, it's not leaking any more. You could also rinse the radiator with a hose to remove any residue antifreeze and associated smell.

I'm bringing the X to the mechanic at some point this month to fix an ABS issue, fix my AC issue, and inspect the car. I'm going to have him flush the system again.

As far as the smell this thread was about, it's gone. However, now I can smell an exhaust smell from my leaking driver side exhaust manifold lol
 






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