Topic: 289 CID overheating problem

[tvor]

Hi guys,
I'm finally getting the car out on the road and I'm having trouble with it getting a bit warm.  The gauge on the instrument cluster rides about in the middle and nudges a little to the hotter side.  For just driving around town, I'm thinking that the needle on the gauge should be around the "N" on "normal" rather than the "M".
So, while searching this site, I read where someone suggested using a better thermostat; a Mr. Gasket High Performance Thermostat.  Only problem is, when I look it up on parts house websites, it says it won't fit my car.  I'm thinking that that's because their year column doesn't go back to 1965 (Grrr!).  If I plug in 1968, it says it will work.  To my knowledge, the 289/302 block is the same for many years and that the thermostat housing did not change for all those years.  Am I correct?  If that is the case, then I could feel confident in ordering up the Mr. Gasket 4364 Thermostat.   The other thing I could do would be to put a shroud on to help cool it, but the car didn't come with one, so I really don't want to put one on.  The radiator is only a 2-core, but I'm pretty sure that's what it had when new as well (it looks to be a replacement because there are no Ford markings on it).

Any other suggestions?

Thanks agin for your help!

PS.  I posted final pics of my car at the Lounge, if you're interested http://www.concoursmustang.com/forum/index.php?topic=13740.new#new

[mgmradio]

Sounds like you are chasing a problem that dosnt exist . The temp gauge should read in the middle of the gauge , give or take a little. If you have a digital/laser thermometer , you can check the actual temp of the motor is.

[WT8095]

Agree completely with mgmradio. Those gauges weren't precision, calibrated instruments to begin with - that's why they don't have numbers marked on them. After 50 years they're probably a little further off. Check the temp with a more accurate instrument and I believe you will find everything is OK.

[CharlesTurner]

Most early Mustangs I've had with normal operating engine temps had the temp gauge reading at about the 1/4 mark.  In traffic, stop and go, they get to halfway to 3/4. 

Agree with Mike that you should get a laser temp reader to get a true reading.

[Richard P.]

Make sure that you have the correct temperature sending unit. A incorrect unit will affect the reading at the gauge.

[tvor]

Thanks for the ideas guys.  The laser temp gauge is now on order from Amazon. I'll play with it this weekend and let you know what I come up with.  I also have a Fluke meter with a temperature sensor.  If that doesn't work, I'll use a candy thermometer to get the water temp reading at the radiator.

The other thing I forgot to mention is that once I park it, it always pukes a nice little puddle from the radiator overflow.  It could just be a bad cap, but since the gauge is reading higher than I remember it, that' is why I'm thinking it's running too hot.

If I find that it is truly running hot, the first thing I want to try is that high performance t-stat (the engine was rebuilt, so it was hot tanked and flushed and there is a new water pump on it.  I've put those two items low on my list of possible problems).  So is a 1968 t-stat size/shape the same for a 1965?

Thanks again for your help!

[carlite65]

how far are you filling the radiator? just barely above the top plate should be fine when cold.

[Building 3]

I have had two experiences with overheating:

I had the same problem when I bought a used Mustang in 1977. It ran hot all of the time. With 120,000 miles on it in 1989 I had the engine rebuilt. It ran hotter after the rebuild. The gauge would peg itself at maximum after only a few miles of driving.  It would spit the coolant out of the overflow, the engine would make those cracking sounds of a too hot engine, and the engine compartment heat was unbearable. The culprit was that the cylinder head bolts were not torqued properly and the rebuilder put the right side head gasket on backwards. After fixing the torque and the gasket it ran fine.

Now I own two 1966 Mustangs. One temperature gauge has the needle centered right in the middle after warm up. The other one has the pointer toward the hot line but not quite on it.  I used the laser thermometer  on the various engine components on both cars. All of the temperatures were about the same. So the "hot" car has a faulty gauge or sending unit or both. Neither car splits out the coolant after a drive.

The laser thermometer is key especially if you can compare the temperatures to other cars.

By the way, you have a beautiful car with a very nice story.  Nice restoration

[Brian Conway]

Some numbers and pictures for comparisons.  Running temp 180 degrees on the thermometer, in the radiator, and on the dash gauge.  Ohm reading from the temp. sender at the same 180 degree temp.  Brian

[tvor]

how far are you filling the radiator? just barely above the top plate should be fine when cold.

yes, just over the top of the core tubes.  It pukes out enough where the level is then below the top of the core.

Rebuilt engine (honed and larger rings installed; not bored), new water pump, new hoses, 180º standard t-stat.  Radiator looks clean and flows well.  I can't remember when it was rebuilt/replaced

[tvor]

Some numbers and pictures for comparisons.  Running temp 180 degrees on the thermometer, in the radiator, and on the dash gauge.  Ohm reading from the temp. sender at the same 180 degree temp.  Brian

Thanks Brian!  That's a great base point

[tvor]

I have had two experiences with overheating:

I had the same problem when I bought a used Mustang in 1977. It ran hot all of the time. With 120,000 miles on it in 1989 I had the engine rebuilt. It ran hotter after the rebuild. The gauge would peg itself at maximum after only a few miles of driving.  It would spit the coolant out of the overflow, the engine would make those cracking sounds of a too hot engine, and the engine compartment heat was unbearable. The culprit was that the cylinder head bolts were not torqued properly and the rebuilder put the right side head gasket on backwards. After fixing the torque and the gasket it ran fine.

By the way, you have a beautiful car with a very nice story.  Nice restoration

How did you identify that the head gasket was installed wrong?  And thank you for the compliment on my car 

[67gtasanjose]

How did you identify that the head gasket was installed wrong?  And thank you for the compliment on my car 

The one time I found one with a head gasket in wrong...the lower radiator hose tries to "suck in" when revving up the engine. I don't think old school gaskets had external markers like many of todays gaskets do. The one I found on wrong was on a Used Car with a 400cid engine, a fellow GM mechanic at the Caddy Garage I was working at put it in backwards & never could figure it out...even after pulling the heads a 2nd time  Poor ole' Oakie quit his job of over 7 years because that smart-a$$ "kid" figured it out! (GM cars usually right/left, front/back is same...basically GM's were "Dummy-Proof"  )

I seriously doubt if you are not boiling over and puking antifreeze everywhere that you might have a head gasket in backwards. The effects would be fast & furious if it were true.

[Building 3]

When we found that the torque was wrong on the heads we pulled them both to see what was going on. Also found a few pistons in the wrong way. So it is an understatement to say that it was a poor rebuild. It has since been redone.

I just drove my car to warm it up. Here are the temperature readings for you to compare when you get your laser thermometer:
Outside ambient: 75F
Top of radiator: 166
Left radiator strap: 110
Right radiator strap: 101
Top of water pump: 188
Top right cylinder hear near dip stick: 170
Top left cylinder head same location: 168
Intake manifold #5: 172
Intake manifold #1: 188
Left valve cover: front to rear: 138-145
right valve cover front to rear: 154-180
Front bottom section of oil pan: 154

[tvor]

Hi all,
So I installed a 160º Mr Gasket High performance (high flow) t-stat (part #4363) and the car is running beautifully!  I decided to go with 160º because I'm in SoCal and if the weather gets below 60º, I'm not going outside!  There's more concern to keep it cool during our summer days of 100º+

My original concern was weather or not the Mr Gasket t-stat would fit, since all the online parts businesses (NAPA, AutoZone, O'Reilly's, etc) did not go back to 1965.  So if anyone is reading this and has the same concern, it fits.  So will the #4364 180º unit.

Building 3 - thank you for those temp measurements!  I'm right in the ballpark and I will keep your data as a baseline in my notes for future sampling as well

Thanks again everyone!