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300 c.u.i Hot and cold together??? Problem solved update

Posted: October 11, 2017, 5:24 pm
by Mr. Jones
My 350 is the shop for some tune up work,Jack calls me today and says #1,2,3 cylinders are reading in the 450 degree range and that #4,5,6 are showing a temperature in the 200/250 degree area measured on the exhaust manifold,using a thermal measuring device. I told him to proceed with a compression test and call back tomorrow.Also had a Pertronix Ignitor installed with Flame Thrower coil.Engine was down on power and my tune up last week did not help much that's why I let the pro's have a go at it ........Any thoughts on a condition like this??
Thanks
Dan

Re: 300 c.u.i Hot and cold together????

Posted: October 11, 2017, 9:17 pm
by slick4x4
Sounds like a coolant flow problem

I had a dodge that had a piece of tin tube in the head
If it wasn't installed, coolant didn't flow in the back

Not sure if a 300 has such a device

Weak water pump ?

450 sure seems extreme though....
Can't hardly believe that type of heat

Re: 300 c.u.i Hot and cold together????

Posted: October 12, 2017, 11:33 am
by Toyz
At those temps, sounds like you have some cylinders not working well, or at all. I’d be looking toward a common problem affecting those three cylinders, assuming common manifold.
Spark plug condition should have provided a clue; compression check will pretty well tell the tale as to mechanical integrity. That leaves the FAST part of the CFAST equation! Got the C(ompression), that leaves the Fuel, Air, Spark, Timing:

Re: 300 c.u.i Hot and cold together????

Posted: October 12, 2017, 1:00 pm
by ThinLizzy13
Do you have the later style two piece dual exhaust manifolds on it?

Re: 300 c.u.i Hot and cold together????

Posted: October 12, 2017, 5:55 pm
by Mr. Jones
Not split,the old style one piece......how might that play into it??

Re: 300 c.u.i Hot and cold together????

Posted: October 12, 2017, 6:39 pm
by ThinLizzy13
Mr. Jones wrote:Not split,the old style one piece......how might that play into it??
I was just taking a shot in the dark that *maybe* if you had the split manifold then *maybe* the front three cylinders' exhaust was plugged somehow.

This is a real head scratcher...did your mechanic have any suggestions after your compression test?

Re: 300 c.u.i Hot and cold together????

Posted: October 12, 2017, 8:45 pm
by slick4x4
Are you running a 2 bbl carb ?
Could one side be running leaner ?

Re: 300 c.u.i Hot and cold together????

Posted: October 13, 2017, 6:10 am
by Mr. Jones
Called Jack back yesterday,cancelled the compression test....$85.00hr.The engine runs better than when it arrived so I'm getting it home and do that test myself.....that won't be until next week..Will post the results then and at their hourly rate the comp.test money will buy a decent infrared detector........meanwhile I'm open to all info....
This post is in a state of temporary suspension........I'll be back........
Pat,Brandon and Paul thanks
Dan

Re: 300 c.u.i Hot and cold together????

Posted: October 13, 2017, 9:31 am
by slick4x4
I bought a cheap detector from harbor freight
I ain't a fan of Chinese stuff
But it was only like $30
Works ok.. red laser dot ,not very bright
Digital readout kinda small
Not for a mechanic that would use it everyday
Ok for somebody that rarely uses it

Re: 300 c.u.i Hot and cold together????

Posted: October 13, 2017, 10:01 am
by longcabjohn
I would check timing on the 4th cylinder in rotation which I think is 6, it should show the same as 1 if different a broken cam could still be turning but be a few degrees late.

Of course this is from the SWAG method.


Johnny

Re: 300 c.u.i Hot and cold together????

Posted: October 17, 2017, 3:43 pm
by orangeRcode
Dan, this isn't the one you recently did a light freshen on was it?

Re: 300 c.u.i Hot and cold together????

Posted: October 17, 2017, 6:00 pm
by Mr. Jones
Robb,
That one was in my 66 250,this is the gray 350 we rode in at Salina....

Re: 300 c.u.i Hot and cold together??? Problem solved updat

Posted: October 24, 2017, 12:38 pm
by Mr. Jones
Got a call from Jack,Friday.Told me they found a broken valve spring on #4 making it run really cold,so that was pulling heat away from 5&6 .....picked it up a couple hours ago drove it to the job picked up all the extra material and returned those drove back to the job unloaded all the trash outta the 250 into it,should have a couple tons in by quitting time......The shop installed the Pertronix,adjusted the valves and a tune up adjusted carb......engine is so smooth at idle it's hard to hear,tested it on a long steep hill made power all the way up....spent the last two weekends doing brakes on the 250 and it's done.Fiqure between what I did myself and the shop both jobs cost me about $460.00 each I'm happy with that
Dan

Re: 300 c.u.i Hot and cold together??? Problem solved updat

Posted: October 24, 2017, 1:11 pm
by unibody madness
Good to hear, would like to find a mechanic that does not charge over 100.00 dollars an hour, and actually knows how to work on these. All I can find are high dollar...low knowledge type r and r shops.

Re: 300 c.u.i Hot and cold together??? Problem solved updat

Posted: October 24, 2017, 2:44 pm
by orangeRcode
unibody madness wrote:Good to hear, would like to find a mechanic that does not charge over 100.00 dollars an hour, and actually knows how to work on these. All I can find are high dollar...low knowledge type r and r shops.
Agreed, it is becoming a lost art. Asked about points and distributors at a local O'Reilley's parts counter and see what you get. Deer in the headlights. Actually had a kid working the counter tell me he knew nothing about how they worked or how to look them up. When you hear that you walk out the door and try and find a better parts counter guy.

That's great news Dan! Glad your girls are back up and running good.

Re: 300 c.u.i Hot and cold together??? Problem solved updat

Posted: October 26, 2017, 4:00 pm
by Toyz
Good deal, Dan, gotta love the modern technology. Back "in the day", the thermal measuring device consisted of a body part!
i do miss the old diagnostic scopes, though!
Paul

Re: 300 c.u.i Hot and cold together??? Problem solved updat

Posted: December 3, 2017, 7:56 am
by deadheadno1
Sigh......., I remember when anything built after 1948 I considered a "late" model. What happened?