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So I just added a bunch of straight antifreeze to what I know was a mostly WATER to antifreeze mix. Greatly water by proportion...
I don't mean to be one of those guys that starts a crazy forum go around but I do,,, I have real questions. I mean SHOOT - It could be that I didn't do a good job bleeding the beast!?
I was running that mostly water mix for a long time. Engine stayed well below N in the center almost all the time. After doing some work in the last days, I refilled to give a 50/50 deal, maybe even a little higher than 50% antifreeze and now,,, she's running WAY hotter than she had. At N or a good bit above. It wasn't even hot this evening.
So, for the summer, is say 20% antifreeze, 75 - 80% water the way to go?
Does water do a better job of grabbing onto heat and carrying it away? I'm wondering.
What say you?
Be gentle with eachother, lol
I know how these things can git.
Yes Water is better at transfering heat, you will see faster needle fluctuations but you will need 15-20% pure anti freeze to maintain some lube and corrosion properties. My Jag mechanic recommends this setup with a bottle of water wetter.
Water is dry and the wetter makes it glide better something to do with surface tension inside the system. Just dont forget it around winter time or a frozen block could end the car.
Last edited by VancouverXJ6; 06-27-2020 at 08:25 PM.
Pure water is about 15% better at conducting heat than glycol. However, the cooling system is designed for a 50/50 mix, so that isn't your problem.
The water glycol mix gives a lower freezing point, plus a higher boiling point, so you are protected both summer and winter. The other thing to consider is that the coolant has corrosion inhibitors in it, water does not and you have dissimilar metals in the engine and cooling system, so those inhibitors are necessary. They do get depleted over time, that's why there is a recommendation to change the coolant periodically.
The V12 can be tricky to fill, so if you have been doing work on the cooling system my guess is that it is not fully filled. Doug has a great writeup on his filling procedure in the archives.
Yeah prettymuch need to put the front on ramps with the left side (left as in your left if sitting inside) and ensure the air is all out from that bleed hole.
I concur. If suddenly you're running noticeably hotter you PROBABLY didn't get it bled adequately.
The only other choice is that you have somehow caused the system NOT to be able to hold pressure. A pressure tester is the way to make sure; you pump it up to 20 psi or so and th eneedle SHOULD NOT MOVE for 20+ minutes. If it falls, youv'e got a drip, a leak somewhere causing the system not to hold pressure, it will CONSISENTLY run 20F hotter than normal under these conditions.
50/50 coolant water, always, but 30/70 in either direction won't kill you (except in sub-freezing weather) , 60/40 is "close enough"
"Water Wetter" IMHO is snake oil and will NEVER cure a cooling system with a failure of any sort - including a single loose hose clamp.
Do NOT flush cooling systems with caustic "coolant flushes." Never ever ever. DRain and refill with fresh. I'm so tired of explaining why you can either listen to me or learn the hard way, I don't care.
I have never, ever been bested by an overheating Jag, if you get into trouble pm/call me.
Last edited by wadenelson; 06-28-2020 at 12:33 AM.
For me, the clarity provided in these posts is GREAT! Puts real numbers and ideas to what I was thinking and had been experiencing, I think...
What I had before must have been something like 20% antifreeze - maybe less. This was good. Yes, I could have mistakenly mis-bled the system, but I think it's more to do with the ratio of coolant to water now. I'm going to go back to the way it was prior to the top end work and replacement of the rear most coolant lines. I finished that up yesterday.
This morning, just in case, from cold, I jacked up the front of the car til the wheels were off the ground. It was already on an incline, nose up. I opened the main fill point and opened the bleeder. Started it. It wouldn't take much more water. When it reached the point of spilling over the main fill point I capped that. Then, only coolant came out of the bleeded point. Very little if any air. I let it idle up to temp. Not much air. Rev-ing by hand,,, still not much air.
It is hot here, yes... After trying to bleed, taking a trip to the sea, the needle is up just a bit past normal "N" electric fan running... Maybe this is "normal". But I prefer the cooler run,,, the way it was before.
The water wetter is a great idea and ive already ordered some. TY for that...
Question, can anyone help OP with the correct bleeding proceedure for HIS Jag?
I know on my SC400 I fill the manifold till it overflows, screw the plug in, then run the motor with the RADIATOR CAP OFF until the t-stat opens, the level drops noticeably and it drinks usually another half gallon or more of coolant.
I'm thinking OP may not be doing step #2 fully or completely.
V12 coolant bleeding can be a PITA but getting all the air out is 100% essential. I've done it many times; sometimes you have to repeat the process. If there's any doubt, there is no doubt: bleed again.
One clue that you still have air in the system is a wandering temp gauge reading.
Not mentioned in the write-up:
Adding a flushing tee to the upper heater hose increases your chances of success. The idea is to uncap the tee and bleed from there first. Then bleed from the bleeder hole in the radiator.
This morning, just in case, from cold, I jacked up the front of the car til the wheels were off the ground. It was already on an incline, nose up. I opened the main fill point and opened the bleeder. Started it. It wouldn't take much more water. When it reached the point of spilling over the main fill point I capped that. Then, only coolant came out of the bleeded point. Very little if any air. I let it idle up to temp. Not much air. Rev-ing by hand,,, still not much air.
"Not much air" isn't good enough.
You want a steady stream coming out of the bleeder hole, shooting up 8-10 inches, like a geyser. When it starts geyser-ing, let it geyser away for a 15 seconds or so to make sure you're not getting faked-out. I've been fooled before by a momentary geyser.
You want a steady stream coming out of the bleeder hole, shooting up 8-10 inches, like a geyser. When it starts geyser-ing, let it geyser away for a 15 seconds or so to make sure you're not getting faked-out. I've been fooled before by a momentary geyser.
Cheers
DD
Thank you Doug. I'll drain it and do it again! I felt I had it right but absolutely might have been faked out! Have been before.
I concur. If suddenly you're running noticeably hotter you PROBABLY didn't get it bled adequately.
The only other choice is that you have somehow caused the system NOT to be able to hold pressure. A pressure tester is the way to make sure; you pump it up to 20 psi or so and th eneedle SHOULD NOT MOVE for 20+ minutes. If it falls, youv'e got a drip, a leak somewhere causing the system not to hold pressure, it will CONSISENTLY run 20F hotter than normal under these conditions.
50/50 coolant water, always, but 30/70 in either direction won't kill you (except in sub-freezing weather) , 60/40 is "close enough"
"Water Wetter" IMHO is snake oil and will NEVER cure a cooling system with a failure of any sort - including a single loose hose clamp.
Do NOT flush cooling systems with caustic "coolant flushes." Never ever ever. DRain and refill with fresh. I'm so tired of explaining why you can either listen to me or learn the hard way, I don't care.
I have never, ever been bested by an overheating Jag, if you get into trouble pm/call me.
For the love of God Man,,, settle down...
I'm not stressed. I don't see the need to be.
I'll redo the filling and bleeding.
ill drain the whole thing.
Mainly, I was and am interested in people's thoughts about H2O and Coolant proportion/ratio ideas and the properties and characteristics of Water vs. Coolant. And such. I got a LOT of good answers. Thank you.
Sometimes I do a general search about stuff like this and there are way too many opinions on the web. Can leave feeling more confused than less. There are some super experienced and trusted voices here. So I ask,,, here, when I get frustrated or confused with Google info.
Remember. I have only been wrestling with automotive questions like this for about 3yrs. Now I have 4 old cars all acquired at various states of BROKEN, small budget and not the best facilities for the work. So, I ask.... Jus say'n.
JJJ
Heater should be on DEFROST while filling and bleeding, engine running once the coolant is topped up as far as possible engine off.
Got ya... Didn't know the DEFROST bit. Was filling as much as I could engine off. Then filling with the heat on HIGH. Also, when I had intakes and cam covers off (NO MORE OIL LEAKS I'm happy to say!) I removed allllll hoses at the rear of the engine, the AAV off the rail, and replaced the small hoses coming off and going into the tubing on top of the Rad at the front of the engine... I NEVER fully drained the system at the bottom of rad with plig or large lower hose(s). Foolishly (I guess) I tried to button everything back up and bleed without a complete drain. I'll do this Friday morning.
The needle will get up to just above N after running for hours in 90+heat,,, my needle seems predictability responsive/accurate,,, so I'm not overly nervous. But I can and will do a better job this Friday.
After reading this thread, I'm nudged to politely ask why you're leaning that way?
Isn't the car engineered to use 50/50?
Isn't there potential for actual harm from using a higher water mix (corrosion)?
Doesn't a properly functioning cooling system maintain the proper temperature (not too high/not too cool)?
Are you perhaps risking hiding a problem rather than getting the system properly sorted?
I hope you find this helpful in your thinking. I've been reading XJS forums forever, and the only improvement to the cooling system from stock that I can recall working out for anyone was switching to electric fans.
After reading this thread, I'm nudged to politely ask why you're leaning that way?
Isn't the car engineered to use 50/50?
Isn't there potential for actual harm from using a higher water mix (corrosion)?
Doesn't a properly functioning cooling system maintain the proper temperature (not too high/not too cool)?
Are you perhaps risking hiding a problem rather than getting the system properly sorted?
I hope you find this helpful in your thinking. I've been reading XJS forums forever, and the only improvement to the cooling system from stock that I can recall working out for anyone was switching to electric fans.
All good points and questions...
Although the ambient temp was a bit cooler at the time, the car was running MUCH cooler before I removed the intakes and cam covers - and always had been. While doing that job I replaced hoses to heater tap on the back of the engine.
In replacing coolant I bought a bottle of antifreeze and topped up what was left in the system shifting the ratio of coolant to water pretty dramatically... Also replaced the yellow cooling fan with the black updated version.
It's VERY possible, as people pointed out here, that I got the refill and bleed of the cooling system WRONG, which could be the reason for my hotter running. That very well could be. Its very possible that I have mistakenly attributed the difference to a higher percentage COOLANT to H2O.
Still, as was stated by others, it's not unheard of to run a mix of 40/60 of even lower percentages of coolant to water,,, water being the higher... Its what I had before and it seemed just fine.
75% water / 25% Antifreeze is pushing it. That formulation, if exact, offers freeze protection until about 10 degrees F and enough corrosion protection the softer water here in NYC. It rarely gets down to single digit temps here. Even if it does water / glycol mixes get slushy before they're freeze solid so you block wont be effected. Still a bit risky though and I dont think a 75/25, 60/40 or 50/50 mix will offer any noticeable cooling difference outside of a lab. It's more likely your radiator needs to be cleared of debris, you fan clutch is week or your auxiliary cooling fan is not working. There lots of small tree bits that a working V12 cooling fan will hoover up and mess up air flow. I know from experience a car with a margin cooling system can over heat when ambient is 80 but operate fine when ambient is 70. I'd invest in a new clutch fan, they're a bargain on Rock Auto and I've done two that have lasted. A proper working fan clutch on a Jag V12 should offer up a tornado like experience off idle when hot. Also you have to check both Thermostats. Thermostats can fail in a way where they get stuck or only open partially. Two thermostats in a pot of just simmering water can tell the story. My wife loves me when I do that. A gradual and smooth opening can and should be observed.
Water wetter is not a scam. Many race tracks don't allow Water / glycol mixes becasue its difficulty to clean up and a small leak from a novice driver off the line can leave a slick spot in the groove. A minor crash could make the track unusable and subject to a lengthy clean up. Water wetter is popular but some guys just run dish soap to break the surface tension of the water. Non-Ionic surfactants found in some brands of dish soap can accomplish same things. They offer some lubricity and break the surface tension. Little corrosion protection though.
06-27-2020, 07:32 PM
H2O or Antifreeze - What's the Skinny
