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High Temps

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High Temps

Post by spatt on Sat Sep 24, 2016 11:51 pm

I have a classic roadster sebring mx with a windsor 351. My temp gauge always seems to run very high at 225-250 range. My temp gauge only goes to 250. I swapped out the radiator cap and put a 13lb cap on it. I also have a radiator overflow tank/bottle on it. So far, I have never overheated, but am getting worried. H s anyone else experienced this? Could it be a bad temp gauge? Also, would adding side vents behind the front wheels help move the engine air out from the engine compartment? Thanks jeff

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Re: High Temps

Post by David V. on Sun Sep 25, 2016 12:40 am

From my experience 250 is pretty dangerously high for long-term operation. Mine usually runs anywhere from 160-200. Might want to start by taking a quick read through this related thread, quite a few suggestions in there: [You must be registered and logged in to see this link.]

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Re: High Temps

Post by aronhk_md on Tue Sep 27, 2016 8:55 am

Hi Jeff

My temp gauge reads 20 degrees higher than the reading I get using my harbor freight infra red heat gun. I'm still running a bit warmer than I want to, and I think the little pusher fan on the front of the radiator isnt enough.

I am fitting a Lincoln MK VIII fan to go in it. One of the most powerful fans ever made and capable of 4000-5000 cfm.

I also think the air in the engine compartment is fighting to get out under the car against the stream of air flowing under there while moving. This is a proven phenomenon in other applications. I too am planning to add a pair of vents. I started looking for a pair but got lost in the 150,000 vents available on ebay. Not sure yet what to get.

Another thing to check is ignition timing. Advanced timing can lead to detonation and hard starting, and sometimes build extra heat slowly. Retarded timing definitely can lead to overheating as the exhaust valve is opening while gases are still burning. This heats the valvetrain components more.

A lean carburator will also cause overheating.

We aren't far from each other. I'm down in West Chester. Maybe sometime we'll get to hang out at a cruise night or car show.
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Re: High Temps

Post by Hotrod on Tue Sep 27, 2016 9:44 am

aronhk_md wrote:My temp gauge reads 20 degrees higher than the reading I get using my harbor freight infra red heat gun.

Where is your temp sending unit? If it's located in the head, it will sometimes pick up heat from the exhaust manifolds. The engine compartment of the Sebring is so tight, this is a possibility. I always run mine in the intake manifold near the thermostat.

The Healey works rally cars had rather large vents installed in the fenders. They had heating problems with hopped up inline sixes so we're bound to have issues with our over stuffed V8 engine bays. Not much room for air flow. Like you, I will be adding fender vents. Too bad, Classic didn't make the louvers in the hood functional. That would have went a long way towards solving the air flow issues.

Make sure that the vacuum advance is functioning. The diaphragm will deteriorate over time. When I was running the stock crate motor in my Sebring, The final piece in solving my overheating problem was going from a 14* vacuum can to an 18* can.
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Re: High Temps

Post by aronhk_md on Tue Sep 27, 2016 9:56 am

No, the sender is in the manifold water passage, and the IR readings right there were around 20-22 degrees lower than what the gauge said.

Its a brand new Billet MSD vac distributor that the previous owner installed. A spendy piece at almost $500.

I too have thought about making the hood louvers functional, but damned if it wouldn't be a lot of work. lol Have also considered just making one functional vent at the rear of the hood that can be opened or closed.

It is quite possible that air flowing under the car curls up behind the radiator creating a high pressure area there and inhibiting flow through the radiator.
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Re: High Temps

Post by Hotrod on Tue Sep 27, 2016 10:29 am

Yea, I agree that the louvers would be a ton of work. You would have to make a template or it's doubtful you would ever get them consistent.

I thought about reversing the hood opening so that it opened from the rear like a Cobra. With a little ingenuity, you could come up with a latch that would allow you to open the rear of the hood slightly from inside the car for additional airflow when needed.
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Re: High Temps

Post by aronhk_md on Tue Sep 27, 2016 10:34 am

I'm guessing you have a hood with the forward hood opening? Cant quite see in your little pic. But reversing it wouldn't likely be enough. It would need to be farther back on the hood.

I keep trying to recall where I have seen a little lever operated hood or cowl vent on some smaller car...an MG? The camaros had one I think on the cowl hood?
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Re: High Temps

Post by Hotrod on Tue Sep 27, 2016 12:45 pm

Sorry, I didn't explain myself clearly. I thought about opening the entire hood from the rear (windshield) with the hinges in front near the radiator. This would allow a lot of air to escape when needed.
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Re: High Temps

Post by aronhk_md on Tue Sep 27, 2016 2:06 pm

Oh. I see what you mean. Yes, have seen that trick done before, and also using spacers to lift a hood off the rear hinges permanently. But I dont really like the way that looks. I also think it will make access to things more difficult with a reverse hinge.
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Re: High Temps

Post by spatt on Tue Sep 27, 2016 11:54 pm

Thanks for the info from everyone. Before I start with your list, I may have gotten lucky because when I started it the other day, my water temp dial went all over the place immediately and then stuck to the 250 degree mark. I let it run a few minutes with the dial at 250 and then checked the hoses. Warm but not hot. So, I guess I may have a short or a faulty temp gauge. And thanks aronhk_md, I live south of the lehigh valley which is not far from you at all. I have not attended any shows yet since I have just bought my sebring recently. Tomorrow I am headed to carlisle show to hopefully buy some misc parts.

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Re: High Temps

Post by David V. on Tue Sep 27, 2016 11:56 pm

Also sounds like your thermostat may not be opening if your hoses feel colder. How does the intake/or valve covers, and how do the heater hoses feel in that situation? (Careful not to burn yourself on the intake). Might want to check if a friend has one of those electronic temperature checker tools
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Re: High Temps

Post by aronhk_md on Wed Sep 28, 2016 12:35 am

I have one of the IR temp guns. I thought about going to Carlisle but I'm busy Sat and Sun I have to drop off some new parts for my 555 twin turbo build for my 73 trans am to a guy in DC on Sunday. He's doing some work on them.

But I just bought my car recently too...middle of August. And the clutch cable broke on me the other day. Had to get towed home. lol
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Re: High Temps

Post by David V. on Wed Sep 28, 2016 1:23 am

Carlisle sounds like a boatload of fun!
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Re: High Temps

Post by aronhk_md on Wed Sep 28, 2016 1:47 am

Carlisle has many different types of car show/swap meets throughout the summer. Ford ones, GM ones and Mopar. Its a massive place. But spring and fall are the general shows where everyone goes. Traffic backs up for miles. You can walk all day and not see it all. I do very much enjoy it. But in my opinion the spring one is the best.
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Re: High Temps

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