The Camaro Club (UK)
http://classiccamaroclub.mfatw.com/

overheating.
http://classiccamaroclub.mfatw.com/viewtopic.php?f=3&t=5189		 Page 1 of 2
Author:  boyzee [Mon Feb 20, 2017 5:09 pm ]
Post subject:  overheating.
My 68 camaro,s temperature runs at around 170F while driveing but in traffic this rise,s to around 200F after about 5 minutes idling.The car has a large Alloy rad 28 1/2 inch across 18" deep an 3 core with 2 11" fans with a proper shroud.After sitting in traffic with the 200F the fans don,t bring the temp down at all but as soon as the traffic clears within a mile of driveing the temp fall,s back to 170F.I have fitted a 180F thermostat instead of the 160F that was in the car but this has,nt made any differance.I was thinking of buying a factory fan blade an taking the electric fans off to try an cure this problem.Anyone have any idea,s for a cure?
Author:  sportsroof [Mon Feb 20, 2017 7:24 pm ]
Post subject:  Re: overheating.
Electric fans may not be able to do what you want. Long story short, I had overheating in my racer when I upgraded the engine, previously the electric fan kept perfect control of the temps. New engine just got too hot and the fan couldn't do the job. I refitted a factory 7-blade flex-type fan at the same time as a shroud the seal the rad to the fan and force all air to go through the rad instead of sneaking round the side. Last time out racing, couldn't get the temps up! And that was a 30 minute session.
HTH
Cheers, Martin
Author:  78 Camaro [Mon Feb 20, 2017 7:41 pm ]
Post subject:  Re: overheating.
Does it ever go over 200f? I'll have to convert to C to help make better sense of the numbers :) 200f is 93c and the optimal temp for an engine is said to be 88-92c so if it's sat at 200f then you're pretty much on the mark. Oil wants to be at about 90c as well for it to be doing it's job in the best way. In perspective, my 3rd gen (admittedly a more modern engine) had it's operating temp at 210f (99c) with the fans coming on at (220f) 104c.

The stocks thermostat for your car looks to be the normal 195f (90.5c) which is about right based on the optimal temp for internal combustion.

In other words, you seem to be ok :)

At 210f you'd want no more increase in temp and 220f it'd be a case of wanting to shut the engine off if it wasn't showing signs of stabilising.

In regards to fan not bringing down the temp when they are on, but driving doing so, is most likely explained by the water pump. As the water pump rpm is linked to engine rpm, slightly counter intuitively, rpm helps cool the engine, because it means a higher volume of water is passing through the the engine (higher volume of water passing through = more water to absorb heat). Interestingly, if you have an owners manual, it says that almost word for word. It mentions that when sat in traffic, to rev the engine slightly (raise rpm) to help push more water through the engine in order to cool it better. Maybe try it next time you're out there - i used to raise rpm to about 1,200 rpm for about 10-20 seconds when the fans kicked in and noticed it cooled the engine faster than without revving. Even though you would think that higher rpm = higher temp. As long as you aren't sat at 2,000 rpm, it won't generate much more heat than at idle, but the water flow will increase by about 50% (based on 800 rpm idle).

An alternative would be an electric water pump, that would ensure high flow at idle and you can keep it on a couple of minutes after switching the engine off if needed.

And +1 on what Martin says about the shroud (Martin knows his stuff!). A shroud makes a noticable difference (i'm planning on making one for mine as it's currently just a fan tied to the radiator).
Hope this helps...
Author:  boyzee [Mon Feb 20, 2017 8:49 pm ]
Post subject:  Re: overheating.
Thanks for both your comment,s the shroud on the fan,s completely covers the engine side of the rad with flaps that open when the car is on the move an close when the fans are on.I will try another gauge to be sure the one i have is accurate it is non electric and i will buy another non electric.The water pump pulley looks larger than stock an may be the problem as you say it may be turning to slow on idle as when i went out in the car last weekend the car was ticking over at 1300rpm,it is cammy an manual an the temp seemed to stay at 200F in traffic but it will rise after a while.The car can be driven fast on the open road and it won,t get hotter than 165/170F so i don,t think it,s an engine problem.Thanks again.
Author:  chevy-stu [Tue Feb 21, 2017 3:53 pm ]
Post subject:  Re: overheating.
Sounds like your on the right track with the water pump and the pulley ratio maybe.. The standard viscous fan and shroud set up is actually very good, never had an issue with mine.
Author:  boyzee [Wed Feb 22, 2017 6:06 pm ]
Post subject:  Re: overheating.
Quote:
Sounds like your on the right track with the water pump and the pulley ratio maybe.. The standard viscous fan and shroud set up is actually very good, never had an issue with mine.
Thanks Stu,im going to the swap meet at Arena essex in a few weeks so i will buy a fan there an hopefully get a shroud to fit.If the weathers dry on sunday i,ll run it down to Brands to get it noise tested as there,s a trackday there.
Author:  3rdGenmalc [Wed Feb 22, 2017 7:30 pm ]
Post subject:  Re: overheating.
How cold do you want it to be ?
You have to have heat in the motor for it to be efficient...
170 is too cold..200 is okay.
You want at least a 180 thermostat.
Author:  boyzee [Thu Feb 23, 2017 7:30 pm ]
Post subject:  Re: overheating.
Quote:
How cold do you want it to be ?
You have to have heat in the motor for it to be efficient...
170 is too cold..200 is okay.
You want at least a 180 thermostat.
The temperature is no problem driving in fact it,s not hot enough at 170F but in traffic is where the problem is.The temperature just keeps going up even with the fans on in the cold weather we,ve been having.I don,t want to have problems when it warms up a bit an i get in traffic.I have taken the 160 thermostat out an put a 180 in but i still have the same problem when it,s in traffic.
Author:  78 Camaro [Fri Feb 24, 2017 10:12 am ]
Post subject:  Re: overheating.
My best guesses for idle temp are the pulley ratio and then next would be the shroud. Probably easier and lower cost to fit a shroud, so guessing that could be a good first step.

One thing about thermostats to note is that they aren't strictly on / off. It's a wax pellet in there that melts within a piston, so it has a gradual open and close. I was running a stock 195 stat in mine and in the winter on the motorway the temp could sometimes go as low as 180, on the really cold days even slightly below that (target operating temp from factory for mine is 220). Sidenote, that's why 160f stats aren't the best idea - the number refers to the fully open temp, meaning a 160f could be going as low as 140f which is too far from the engine operating temp and doesn't allow the oil to function correctly i.e. burn off moisture and form protective coatings. Having too low of a stat also means the radiator doesn't hold enough cool water - as the thermostat starts letting small amounts of water through often 20f below it's rated temp, the rad temp doesn't go as low as expected and can't deliver the full cooling effect.

Another thing on stats is they don't set the operating temp, this is set by the combustion in the engine, the thermostat mainly affects the lowest potential operating temp and it sounds like everything is functioning ok on yours as it's able to get down to 170f when driving. So it's really just the idle issue and 195f is about where it should sit, and then the fan should be drawing enough air to stop it going over 210 and keeping it below 220. I wouldn't have an issue with 200f idle and then above that, i would expect it to not reach 220f. From the sounds of yours, it seems to be within range but it needs a little help and as you say, when the outside temp gets warmer, it could end up running warmer. It seems that it could be taken care of with the shroud and pulley and when you're driving all is well.

Sorry for another long reply, hope it helps somehow.

Have you had any luck finding a shroud so far?
Author:  3rdGenmalc [Fri Feb 24, 2017 11:49 am ]
Post subject:  Re: overheating.
Go to Amazon.com or try Amazon uk and search for Purple Ice.....
add a couple of bottles to your coolant.
I have one bottle in mine, come the hot months I'll add another.
Only in the hot months here my motor goes over 200F, when it does it's
undriveable.
Page 1 of 2 All times are UTC
Powered by phpBB® Forum Software © phpBB Limited
https://www.phpbb.com/