engine temp

[BarryK]

The 327/365 motor in my '65 has always run nice and consistent regard engine temp while driving. Never seemed to matter whther it was a long cruise down the highway at 75mph or sitting in stop and go traffic. The temp always stayed rock steadyat 180 and some rare times only on the very hottest days stuck in traffic it would sometimes creep up to about 200 (half way between the 180 mark and the next slash mark which is unmarked).
Last summer I had to replace the temp sending unit and hearing that the replacement are usually off I was concerned but it seemed to be giving me about the same readings - maybe about 10* higher but not more than that.

When it was in the mechanics shop last week he checked the guage and sending unit by comparing to an IR gun and said it was pretty much dead on accurate. He also checked the coolant by checking the PH levels (?) and said it was perfect with a PH reading of 10.

The problem is that the last two days I've had the car out it's definately running a LOT hotter than it was. While cruising down the road it's running steady at about 200-215* but as soon as I hit stop and go traffic or sitting at a light I can watch the gauge just creep up and up to almost pegging it at 240. Once I get a clear road and can run it for a few miles it will start to lower back to about 200* again but as soon as I have to sit at a light or stuck in traffic it starts to move up to almost 240* fairly quickly (within a few minutes).
So far it hasn't overheated and it's not puking coolant when I pull into the garage and park it so any ideas on why this seems to have suddenly started? Do I need a new thermostat?
As always, thanks in advance for all your help.

 

[paul67]

Barry,
A 180 thermostat should be fully open at that temperature and in summer heat never close in driving conditions. It's basically just a warm-up device or conversely if you care to drive at -20* in winter, a device to keep the engine (and you) warm.

I use financial path of least resistance plan at times. In your case I would suspect the thermostat being locked in a semi-closed position and for $10 or so replace it. Then we can go from there. It's a simple job and takes about 20 minutes. My brand of choice is a SuperStat from Stant, available from most auto parts stores. Others have their favourites.

 

[BarryK]

ok, makes sense Paul. For approx $10 I can replace and see if it makes a difference.

now the $60,000 question........ how?
Is it as easy as I'm guessing by what looks like the following steps?

purchase new thermostat and new gasket for TS housing.
remove housing by removing 2 bolts
remove and replace thermostat (is it simply just sitting in there?)
Reinstall housing with new gasket

is it really that easy? Also, is the new gasket I'll probably need also a readily available gasket at most parts stores or is it something I need to order in from a Corvette Vendor like LICS, Paragon, etc.

 

[Mike McKown]

ok, makes sense Paul. For approx $10 I can replace and see if it makes a difference.

now the $60,000 question........ how?
Is it as easy as I'm guessing by what looks like the following steps?

purchase new thermostat and new gasket for TS housing.
remove housing by removing 2 bolts
remove and replace thermostat (is it simply just sitting in there?)
Reinstall housing with new gasket

is it really that easy? Also, is the new gasket I'll probably need also a readily available gasket at most parts stores or is it something I need to order in from a Corvette Vendor like LICS, Paragon, etc.

This may seem a little elementary to you but have you checked the coolant level and made sure it's full?

I've never had a problem with a thermostat sticking closed but I would think if it did, your car wouldn't cool down at highway speeds as your engine puts out more heat at speed, thus needs more water/air flow to cool it.

 

[polish41]

Yes it really is that simple. The parts house should have a gasket for it in stock. Nothing special just a piece of formed paper. Back when I was a kid used to take a cereal box and cut out what I needed. Now I'm showing my age.

 

[BarryK]

Mike
no I haven't i'm embarrassed to say for two reasons......... first, when I noticed the problem this afternoon for the second time I posted about it as soon as I returned so the system would be way too hot for me to open it and check. Second, the car was just gone over thoughly at the mechanics last week including testing the coolant. I would imagine that since he was checking EVERYTHING on the car he checked the coolant level as well as actually testing the coolant ( but I suppose it's possible he didn't).
Ok, a third reason now also....... I don't know what level the coolant is suppose to actually be at. Should the level be full on the overflow tank, or halfway or what? I can look but it won't tell me anything since I don't know what it's suppose to be

 

[BarryK]

thanks Polish

I'll run out tomorrow and pick up the new thermostat and gasket and we will see if it makes a difference. Hopefully it will be the simple fix but with me it's usually anything but simple and easy.

 

[youwish2bme]

Hold up lets think about what was done since the last time you drove the car...UMMMM the timing was changed.. Lets suppose for a second that he never checked to see if the balancer was actually at TDC. You said he got it timed right for you and it runs better.... However we don't know what it's set at now.... Just a thought... Dave...

 

[paul67]

Barry,
Yes it just sits in the intake groove. You will lose some coolant so get a quart or so of the green stuff. The gasket is self-stick and about $0.50.

Dave,
I hesitated to bring up that subject. But this could be a timing issue. Although at 240F this would be an extreme case. That is VERY hot!

 

[polish41]

Oh yes Barry there are a couple of things I didn't mention. You will have to drain the radiator down below the level of the thermostat housing. Then there will still be antifreeze in the hose. Then you will have to burp the system when you refill it. I usually fill the block just below the thermostat. Install the housing then remove the upper end of the hose and fill it. Then fill the radiator to the recommended level. Do you have a overflow tank or just a hose running to the ground? This will determine the level that you fill to.

Paul aka Polish41

 

[BarryK]

Dave
yes, that thought actually occured to me regarding the timing but was trying to HOPE that wasn't the case considering it is running good. Motors run hotter if the timing is retarded right? That's the senario I'm dreading because that means I can't trust this new mechanic to do things correctly either which would be the third one and i'm running out of local mechanics - especially one that can work on older cars. and you KNOW I'm not qualified to redo it or check it myself. Of course it I can just get it to hold together and not overheat or cause any damage I'm having Lars check over and tune my car in Sept but that's a 5-6 weeks away yet including a long drive to and from Carlisle inbetween now and than. :ugh

Paul and Paul
ahh....... having to lower the coolant level wasn't something I had figured on. that complicates things a bit. How do I drain the level down - especially without getting coolant everywhere? Second, burping the system?? how do I do that?
yes, I have the expansion tank on my system but I don't know about any hose running to the ground.

I swear, I'm just destined to never be able to actually drive and enjoy this car - it's just one thing after another and it spends more time in various shops than it does in my own garage or on the road and even than when it leaves a shop there is always something still not right with it!

 

[Subfixer]

Barry, I'm going to take a slightly different approach here.

Having read all your posts about your mechanic's initial problems with timing, and his subsequent repair, that's the first place I'd look. As has been written countless times on these forums, incorrect initial timing has everything to do with high temps at idle.

Since virtually nothing else has been changed on your car in the last few months, that's the first thing to check (again).

 

[youwish2bme]

Barry, I'm going to take a slightly different approach here.

Having read all your posts about your mechanic's initial problems with timing, and his subsequent repair, that's the first place I'd look. As has been written countless times on these forums, incorrect initial timing has everything to do with high temps at idle.

Since virtually nothing else has been changed on your car in the last few months, that's the first thing to check (again).

Paul great minds think alike... Dave..

 

[BarryK]

Paul (Subfixer)
damn, 3 Pauls just on this thread now!
I was thinking along the same lines but was REALLY HOPING that wasn't going to be the case.
You know, I've lost count but think this last shop visit was at least the 6th time in 3 different shops I've had it to somebody to try to get the timing issues worked out (not even counting the one or two times my neighbor tried to help me with it) since I bought it last year. I'm SERIOUSLY getting fed up with this lingering problem and all the money i've had to spend trying to get it right and it's still not. ad
I can't fix it myself as you know so how many more new shops and mechanics and $$$ is it going to take to finally get it right?
Even if I went out, bought the best timing light on the market, and somebody showed me how to use it, I seriously doubt I can find the problem if all these "professional" mechanics who do this for a living can't fix it.
I'm very frustrated about this (as you may be able to tell) and am running out of ideas of what to do about it short of skipping Carlisle (don't want to risk driving her there with it like this), parking her in the garage and waiting until Sept when I see Lars and just hope the car makes the 2/12 - 3 hour drive to see him in NJ.

 

[paul67]

Barry,
When you take the t-stat housing off you will lose about one quart or less of coolant. I'm messy and just let it drip. When you have completed the job just clean up with water.

As for timing, I really do not know what to say. I have a Sears advance unit and it works very well. My setting is 10* initial. I spent most of the day with a chainsaw (older vendors, 80s, little tree maintenance) at the new house but managed a two-hour ride in 85F heat. No problem. Bang on 180F. I wish I could do more but with a grin (no malice intended), I pulled a Barry today. Chainsaw over my head and I pulled a shoulder muscle. Those suckers are heavy and I just turned the wrong way at the wrong time when a large branch came down. So its Advil and heat pad time.

Hope others can sort matters out for you!

 

[BarryK]

Barry,
When you take the t-stat housing off you will lose about one quart or less of coolant. I'm messy and just let it drip. When you have completed the job just clean up with water.

As for timing, I really do not know what to say. I have a Sears advance unit and it works very well. My setting is 10* initial. I spent most of the day with a chainsaw (older vendors, 80s, little tree maintenance) at the new house but managed a two-hour ride in 85F heat. No problem. Bang on 180F. I wish I could do more but with a grin (no malice intended), I pulled a Barry today. Chainsaw over my head and I pulled a shoulder muscle. Those suckers are heavy and I just turned the wrong way at the wrong time when a large branch came down. So its Advil and heat pad time.

Hope others can sort matters out for you!

Paul, I use or have used all kinds of various power tools but never a chainsaw and never plan on ever using one - those things just plain scare me to death for some reason. I always envision something happening and ending up with less body limbs than I started the day with.

 

[BarryK]

oh, I just thought of something else.
When i picked up the car from the mechanics shop last week it was idleing perfect at about 800rpm but than I noticed today that when stopped at various lights or stop signs I had to keep goosing the gas a bit to keep it from stalling and the idle was around 650rpm - about 150rpm less than it had been. A 365hp motor isn't suppose to be able to idle that low!
Do you think it could be something as simple as the distributor wasn't tightened down enough and from driving it loosened up enough to slightly shift causing the timing to go wacky again? The first time or two I drove it after getting it back from the mechanic I didn't see the temps reaching anywhere near as high as the last two times I drove it and it idles great but not anymore.

 

[JL66REDCPE]

Barry - It could absolutely be that the hold down clamp failed for whatever the reason and distributor has moved. They are somewhat tricky to get on properly. Also, some of the replacement bolts from the part houses are too long and bottom out before they tighten the clamp properly. The fact that you now say it is not idling very well leads me to believe this is the problem. Of course it is also possible that your vacuum hose may have come off however it is more likely the hold down clamp.

 

[Vette66AirCoupe]

Barry,

First things first. Check the coolant level. When the motor is cold you should see a little coolant in the expansion tank. If it's there, the radiatior is full. If it's not, add some 50/50 coolant/water mix and take it for a spin. Let it cool down and check it again.

Is the car running strong? Not bogging down at high RPM's? Not pinging? If all of those things are OK then your timing is probably not the issue. If that's the case, here's my suggestion. Go buy a thermostat housing gasket only. You can drain your radiator by turning the pet cock on the bottom of the radiator. It looks like a wing nut with a little piece of tubing sticking out of it. Put a pan underneath it if you want to save your antifreeze. If you take it down about a gallon that should be plenty. Now disconnect the upper radiator hose at the thermostat housing. Take out 2 bolts and pull off the housing. Note the position of the thermostat for future reference. You don't want to put a new one back in upside down later. Clean up and paint your thermostat housing which you mentioned you want to do anyway and let it dry. Make sure you scrape off all of the old gasket from both the housing and the top of the intake manifold. Put the new gasket on and replace the housing. No new thermostat. Go to Carlisle knowing nothing is impeding the flow of coolant in your car and you don't need to worry about burping the system. In the fall, put some radiator flush in your car and run it a while per the directions. Drain and flush the system as best you can which will be much easier without the thermostat in there. Open that pet cock and/or drop the lower radiator hose to let all the dirty stuff out. Put the hose back on (no need to tighten up the clamp at this point) and fill the system with water again, run the engine. Drop the hose again, repeat until the water coming out is clean. Then put the hose back on, tighten the clamp, close the petcock, remove the thermostat housing, put in a new thermostat and gasket, refill the sytem with 50/50 anti-freeze/water mix. All that thermostat will do is help your car warm up faster. This time of year that's of little use. Now in the fall and winter, if you want to drive it, you still don't NEED a thermostat, but what will happen is that with the unimpeded flow of coolant through the radiator your motor will run at about 150-160 degrees if you try to shoot down Rt. 1 at 65 mph+ when it's 40 degrees out or so. That's not a real big deal until your wife starts hollering "Where's the HEAT!!?? ad For what it's worth, I thought my '66 big block had a 165 degree thermostat in it because I had no heat last winter and the gauge said it was around that temperature. Turned out there was no thermostat in it when I serviced the cooling system this spring.

 

[BarryK]

John
I'm still trying to get the car detailed and clean from being in the paint shop, especially the engine compartment and I know I haven't seen any vacuum lines unconnected so don't think that's the problem. If it's just a lossened distributor it would make sennse i'm thinking simply because it wasn't running this hot a few days ago after I got it from the shop inncluding a nice drive in very hot weather up to NJ a few days ago although that was mosly all on Rt 295 so no stop & go traffic or anything. It would be the easy explanation for the problem but i'm never that lucky!

ok.... I just went out to the car and rechecked the vacuum lines - all properly connected. Also checked the tightness of the distributor. With the shielding still in place the only way to really check it was by grabbing hold of the vacuum can and trying to move the distrb. back and forth and I could not bulge it at all so I assume it's not loose afterall. That would have been the nice easy answer though wouldn't it?