Chrysler 300 - The Saga Continues

[gmw photos]

Originally Posted by mstephens

I got my car back this evening. I took it for a small torture test around town and the temp stayed good. While crawling slow for 10 minutes it will get to 215, and when driving fast it goes down to 203. They replaced both heads and somehow manage to get it back together, which amazes me.

Everything feels good. I will take it on a trip tomorrow with no trailer. I have a gentle 2800 foot pass to go over, and it is a 150 mile trip. That should be a final test before we hook and tow once more on Friday. Gee whiz, I hope this is it this time.

Call me sceptical Mark, but I'm not liking the sound of this. How hard is it to change the t-stat in this thing ? I'd see of you can get a 180 degree stat in it ( maybe a motor-rad fail-safe ? ). I have a feeling if with no trailer you are already seeing 215, you're gonna be seeing the dreaded 230+....bells, chimes, etc on a long uphill hot day pull.
The dealer is of course going to say 215 is normal....but then he does not know you are strapping a 5500 pound trailer to the back.....

[perryg114]

Well what is the setpoint of the OEM thermostat? Unless you are really stressing it a 190 degree thermostat should be right there around 190 degrees. My scangage reads 190 when hot on both my fords. They read air temperature before starting up so I know the sensors are good. I would say anything more than 5 degrees above the setpoint is a problem. The question is what is the setpoint? You may need more cooling. On most cars the trans is cooled by the engine coolant.

Perry

[Denis4x4]

I have to believe that the thermostat temp is tied to the computer and to change it would cause even more problems! I ran EFI on a 1931 Ford Model A engine and the temp was critical to the overall performance.

[ggoat!!!]

You would be surprised at how hot Pentastars run. The Pentastar in the Jeep Wrangler consistently runs 220-230 just cruising around town. When the fan comes on it sounds like a locomotive. These engines were originally designed to run hotter for better emissions control, however with the integrated exhaust manifolds built into the heads the heat destroys the exhaust valves. There have been several revisions of the supposed "repaired" heads; I think they are on the "AC" designated ones now (I couldn't keep up with all the revisions). Now, however, the latest Chrysler fix for the Pentastar in the Wrangler has been to adjust the fan temps and to reduce the peak timing slightly. However, people are still having the heads replaced...

Bottom line, however...putting a lower temperature thermostat in these engines will throw all the electrical stuff off regarding the fan temps and such. And, the radiators in these vehicles are marginal at cooling at the temps they are designed to run at; so, even with a lower thermostat all this does is make the computer think the engine isn't up to designed operating temperature which keeps it in "open loop" mode longer while also basically running with the thermostat open most of the time just because the underhood and exhaust temps are so high on these vehicles. And, when a thermostat is opened longer, don't forget that the result is LESS time that coolant has to sit in the radiator and actually cool by airflow.

I learned on the SSR (which characteristically also run hotter because of the limited engine bay space and small radiator) that trying to "outsmart" the factory cooling system by lowering the thermostat is a losing situation for the reasons I listed above.

Running 220-230 in an engine designed for it is fine; the problem with the Pentastar is that the exhaust valves fail from the heat.

[gmw photos]

thanks for the follow on statements regarding thermostats from my above posting.
Perry asked what the setpoint is of the stat, and for sure that seems a good place to start the question process ( better than my blanket statement of simply going to a lower temp stat ).
For what it's worth, just as a data point that has zero relation to the car in question....on my Nissan, the scangage shows it routinely runs right in the middle of the thermostats specified range. It runs at 191 to 195 virtually all the time, although it will occasionally go over 200 especially if it's lugged. It is obvious from a heat standpoint anyway, it does not like to be lugged with the resulting added need for pedal. Downshift a gear, let it spin, and it cools back into the mid 190's.

[Grrrwolf]

Originally Posted by mstephens

But when you open the hood, man oh man, it is jam packed in there....

I suggest if you are able to kill this motor before the warranty is up you try to pay the difference and upgrade to the Hemi. You know they manage to shoehorn 6.4s in those things somehow.

[perryg114]

Let's assume the car runs a tad hot by design. I think that pulling a trailer will require more cooling.

Perry

[SteveH]

If it were mine, I'd see if I couldn't find a bigger radiator for it. Maybe the one they use with the Hemi engine? There's obviously an engine cooling issue, and a bigger radiator is the best way to handle that.

[mstephens]

I drove the 150 mile loop today and monitored temps all the way. 205F seems to the center. I saw it hit 209 for a couple brief moments on the daylight side of the trip. It was around 82F ambient.

On the homebound, it was 72F ambient and the temp ran about 197F almost all the way home.

The 212 - 215F only occurred when I lugged it at 5 MPH for 15 minutes around the compound here. So, I think it is fair to say that while driving 205 - 210F is probably the expected norm.

Now, as to changing T'stats. There are lots of posts on various sites saying that unless you can change the computer settings, changing t'stat is a bad idea. My take away was that the designed temp of 205 is very purposeful and ties to other functions. Since I have ZERO automotive repair chops, I am not willing to begin engaging in engine experiments where I have to rely on mechanics whom I don't know.

Keep in mind, there is a fellow who towed a 25 all summer long in Arizona with this car. So, there is one data point.

This week we will be in the high 80s here. If I can tow up the 12 mile grade in that heat, and measure the temp rise, I think I can have a good reference for what is going to happen.

BTW, the alarm is not 230F, it is 265F.

[Denis4x4]

Try calling SoCal Speed Shop in Pomona as they have tricked out several late model 300's and seem to have a pipeline into Chrysler's tech department. Purchased an oversize radiator from them for my '60 Thunderbird that cured a lot of ills.

[Aage]

Originally Posted by mstephens

This week we will be in the high 80s here. If I can tow up the 12 mile grade in that heat, and measure the temp rise, I think I can have a good reference for what is going to happen.

BTW, the alarm is not 230F, it is 265F.

Sounds like things are beginning to even out. Fair winds and following seas to you!

ps: TOTALLY jealous of the temperatures you are getting there.

[dwilderman]

Originally Posted by mstephens

The saga continues with a big FAIL on the first hill climb. After getting the WD right, the anti-sway bar mounted, and everything cleaned up on the hitch, we wanted to get out on a grade, in the heat, and make sure the rig will get us over these California mountains. It turned into an afternoon in hell.

We chose the medium grade from I-10 up to Yucca Valley on CA 62. This is maybe a 12 mile climb from 400 feet to about 3400 feet and very average for around here. It was about 85F outside. We hustled up about 9 miles at 55MPH in 3rd gear. I had the trans temp gauge selected and was watching it like a hawk. An easy drive. Suddenly in 30-seconds everything changed. I first smelled a foul smell, then alarms went off on the dash for overheating. Dash lights were warning, buzzers going, I slowed immediately and moved to the very skinny 8 foot shoulder and hoped I could climb to a straight part of the road. No luck. The car died on a hard right uphill turn. I could now see steam and smell coolant. The trailer wheels were against the asphalt berm on the right. I didn't dare open my driver door as cars were whizzing by at 65MPH or more.

I was able to get out the passenger side and raise the hood. A mess of blown coolant under the hood. We waited 30 minutes. Two Airstreams motored by and honked (a little disappointing actually). A big commercial tow rig stopped and he was very helpful. He knew the road and told me a big flat spot 1/4 mile ahead had 30 feet of shoulder. If only I could start the car. We took water from the TT and eventually filled the radiator and moved the rig up to the big flat spot, where it was at least safe. We waited another hour then crippled to the next possible place to turn back and go downhill. That was a mile up. We coasted downhill with the temp reading 225F, got home at 245F and unhitched and put the car in the garage.

Took it to the dealer. Turned out the coolant reservoir was cracked and had been leaking coolant (I had smelled a weird smell a few times before in the weeks before. I didn't know it was coolant hitting the exhaust manifold). Also, the rad cap was bad and only holding 10# when 17# was the spec. All warranty repairs. I tried to insist they thoroughly road test the car and look for any other cooling issues. They said they did.

I now have the car back and frankly, I am quite nervous. I will first try the car alone up that same grade. Then I will try the trailer on a smaller, shorter grade somewhere to see if there is any sign of heating. What worries me is that we went from "green light to China Syndrome" in like 30-seconds with basically no warning, no time to do much.

I dunno.

One thing which I haven't seen mentioned are the enormous differences between newer cars and the kind we could buy prior to EPA regulations in the USA. My father pulled a 34' foot AS all over the country with a Chrysler Imperial. (Not sure of the year, but before EPA and probably in the 60's somewhere. Because of EPA and gas mileage requirements, no-one seems to make towing sedans anymore. Even finding an SUV to meet the requirements can be a challenge. I'm afraid the day of towing much beyond a small utility trailer with the "family car" is history. That's one of the main reasons I use a Class B MH rather than tow a Trailer. Personal preference in a radically different environment than 40 years ago. IMHO, best overall options are among the 1 ton vans, if you prefer to tow.

[dznf0g]

Originally Posted by dwilderman

One thing which I haven't seen mentioned are the enormous differences between newer cars and the kind we could buy prior to EPA regulations in the USA. My father pulled a 34' foot AS all over the country with a Chrysler Imperial. (Not sure of the year, but before EPA and probably in the 60's somewhere. Because of EPA and gas mileage requirements, no-one seems to make towing sedans anymore. Even finding an SUV to meet the requirements can be a challenge. I'm afraid the day of towing much beyond a small utility trailer with the "family car" is history. That's one of the main reasons I use a Class B MH rather than tow a Trailer. Personal preference in a radically different environment than 40 years ago. IMHO, best overall options are among the 1 ton vans, if you prefer to tow.

I believe it to be more a result of CAFE requirements than emissions requirements.

[SteveSueMac]

Sad - just noticed Mstephens hasn't posted since April 2014. I think he got a Suburban after this experiment. I hope he's been having a blast and just too busy camping to post here. This was a really brave experiment.

[jcanavera]

Originally Posted by dwilderman

IMHO, best overall options are among the 1 ton vans, if you prefer to tow.

One caution regarding 1 ton van recommendations. From my experience with 3/4 ton GM vans and one tons, the 3/4 ton vans usually have higher towing capacities when equipped with the same axles and engines. Also note that non factory van conversions have lower tow ratings due to the weight of the conversion components.

Jack

[xrvr]

Agree especially if you are talking passenger vans, the seats are heavy.

[jcanavera]

Originally Posted by avionstream

Agree especially if you are talking passenger vans, the seats are heavy.

If you buy the factory passenger van, the tow ratings accurately reflect those seats. Granted they are heavy. My 3/4 ton van has a 9,900 lb tow rating.

[xrvr]

And that extra row of seats takes away from the payload and possibly the tow cap. I agree, the three quarter is the best choice. Had a half ton van and always longed for a three quarter ton diesel. Take the rear sets of seats out and you gave a huge carrying capacity and can still tow almost any AS.

[jcanavera]

Originally Posted by avionstream

Take the rear sets of seats out and you gave a huge carrying capacity and can still tow almost any AS.

I ordered mine new, and the 3/4 ton passenger van comes with 2 bucket seats and 3 bench seats. I deleted the furthest back bench seat and used the credit to upgrade the driver and passenger seat to 7 way power seats. At the time mine was built, GM wasn't offering a diesel option. I took the 6 liter gas and 4.10 rear axle option to get the big towing capacity. It's the best tow vehicle for my heavy 30' Classic slide out. It's now 12 years old with 39,000 miles. I pretty much only use it to tow and it will probably be the last tow vehicle I ever will own.


Jack

[xrvr]

Oh yea, a great tv.