Just returned from the Promised Land

[Jim Stoltz]

This was the second trip with the newly resurrected Allegro. It was only half the distance as my first excursion, but it was not without issue. Minor issue, but a concern nonetheless.

So I live in Northern NJ and like to avoid the interstates with my '84 Allegro. It's just not built to travel at the speeds people travel these days. 55 is about it and at that speed it's an obstruction. My choices for this trip to the Promised Land State Park were pretty much I-80 W most of the 65 miles or 206 N to I-84. I would be on I-84 for 20 miles. 206 is a nice, slow ride with only a couple of tight spots through congested areas. So, I chose this route.

I didn't realize that this route is pretty much uphill most of the way. It was hilly and twisty as I approached route 84 and then my time on 84 was mostly climbing hills. Temps were in the high-70s. The temp gauge creeped up into the red as I was merging onto I-84. Thankfully there was construction that had the speed limit reduced and people were moving at around 50 MPH. The rig really seems to like this speed. On a flat or downhill run the temp gauge actually swings left of center toward the cool side. But then the hills on I-84 started and by the time I got to my exit I was in the red again. I got off the highway and pulled off to the side to assess the situation. I let it run at about 2000 RPM with the clutch fan roaring. Helped bring it down a bit, but not enough where I felt comfortable driving it. It never boiled over - I was just relying on the gauge. I was 4.5 miles from the campground, but I didn't know what lied ahead hill-wise. It was a 40 MPH road and the part I was on was uphill.

I threw caution into the wind and pulled back onto the road. At 35-40 MPH it cooled down almost immediately.

The ride home today was totally uneventful. It was a few degrees hotter outside, but it stayed cool the whole way home. 

So what are my options to keep this thing cool then? It recovers quick, but I don't like it getting that hot. It's not an airflow thing as it gets hot at highway speeds. It seems like it needs more cooling capacity (bigger radiator?). Water pump is new. I'm not sure it's a flow thing either because if I slow down and drop it to 2nd it cools right down. An electric fan would be good at idle as it does creep up a bit but not what I would consider "hot".

Anyway, the better news is that my GF totally loves the thing. It had been consuming a lot of my time and funds. She referred to it as "the big stupid motorhome" (mostly kidding, but not 100%). Our last trip to the Promised Land was in a tent. She's totally sold on the RV thing. Hook line and sinker. Loved every minute of it (except for the overheating, but she's cool in the face of adversity - pun intended).

Our next trip is to the Pocono Raceway. It's a shorter (45 mile) trip, but it's going to be pretty hot out in August. I'm taking the whole family this time - her kid, my kids, etc. I HAVE to fix the steering by then. The thing is a handful to keep in a lane.

[Jim Stoltz]

I do have an infrared thermometer - I'll check the radiator.

I believe it's a 190 stat. I honestly don't remember - it's what the guy at Autozone handed me. 

Downshifting seemed counter-intuitive to me - higher RPMs seem like it would make it hotter. But it didn't - slowing down and dropping a gear cooled it off. Trouble is that it's dangerous to drop down to 2nd with the TH400. Max is like 40 MPH. 

I had thought about replacing the radiator and installing a trans cooler while I had the engine out. But...the lines seemed to be fused in there and tough to get at even with the engine out. Now, of course, it's going to be even harder to go that route.

While was getting hot I never thought about turning on the heat. Before I left the campground today I swung the HVAC over to HOT so the coolant would circulate in the heater core. Can that make much of a difference? It's more capacity, right?

[Jonas]

Is this a big block gas engine?  I think you should be running a high quality 180 or even a 160 thermostat.

I had a similar issue with the 440 in my Dodge Travco getting hot.  I installed a high flow water pump and a 180 thermostat with no better results.  I went to a 160 stat with no change.  I pulled out the radiator and took it to a shop to have it boiled out.  When I picked it up the guy told me that it was in good shape before the cleaning and really wasn't too clogged in the first place.

Long story short... it turned out to be that I had the wrong radiator cap.  I had installed one of those lever type caps and it turned out that it wasn't making the correct seal as compared to the factory style radiator cap.  Now, instead of running 230 up hills, it runs around 200 - 210 with the 180 thermostat.  It runs 190 - 200 on flat land at 60 mph or so.

Good luck!

[Jim Stoltz]

Yes it's a big block 454. I really should change the radiator cap. It was leaking, but after taking it off and reseating it I thought it was good. When checking the overflow tank today when hot, it was a bit low on coolant but not below the "add" line. I topped it off when I got home. 

I might take the thermostat down a notch or 2. Cooler seems to make more sense. 

[Jonas]

The spring in the radiator cap gets weak over time and won't hold proper pressure.  I would spend a few extra bucks on a good quality OEM style cap.

[paul nevitt]

Hey Jim. What everyone knows and no one like to say is, The P30 Chevy chassis have two huge problems. First and a big one is the brakes, They suck. Next is the overheating. Not much you can do with this in a stock form. I drive mine in the mountain all the time so I know a few things about running hot. The tranny is a big source of heat, Get it out of the radiator. A nice BIG cooler up front 18,000 GVW or even bigger. Next I run a 160 thermostat and water wetter with my anti-freeze. A nice big 18" fan that you can hook up the a thermo switch or dash switch isn't a bad idea. I have a tranny cooler and low thermostat but haven't yet put a fan in. She still runs hot some times and times very close to red but never hot enough to kick the fan clutch on. (yes it does work). Another quick tip is keep the engine rpm's higher then idle but not so high it is making more heat. The reason it cooled down quick when you took off was the speed the pump was turning was moving cool anti-freeze from the radiator to the engine.The radiator is big enough but the water pump and flow through the crappy 80's cast iron heads is not. What I find works best for me even in the mountains is 55-60 mph and try not to following close to anything big enough to block the wind from your radiator. Good luck.    

[Jim Stoltz]

Funny - the fan clutch only kicked on once but not on this trip. It was on the way back from Hershey about a mile from my house. Long hill and it was almost 90 degrees out.

I guess a big trans cooler is in my future. The trans will like it and so will the engine. I can get a cooler thermostat - it's easy enough to replace.

When going through the construction zone they had one of those "Your Speed is this" signs. If they're right, my speedo is reading about 5 MPH slow. So, 55-60 seems to be the sweet spot. 

Brakes - I dunno. It has discs on all 4 corners and seems to do pretty well for what it is. I've had more than a few panic stops as the result of the people that just HAVE to get in front of the monstrosity and it's done well. Yesterday I had a dude on a Harley fly around me, then cut across 2 lanes of traffic to slam on his brakes in front of me to pull into a local bar. Barely got it stopped, and lit him up with the air horns. His passenger flipped me off, but at least no one got hurt. Had a Subie cut in from a turning lane in front of me today, too. Had to brake hard. Took me an hour to find my cell phone after that one. I don't know why people put themselves in front of the thing. 

So, I'll take a look at the cooling system. Getting the hot tranny fluid out of the radiator makes sense, and so does a cooler thermostat. 

Otherwise the thing runs awesome. It moves along really nicely for how big it is. I try to keep my foot out of the secondaries, but when they kick in it's a noticeable kick in the pants.

[John "T" Nordhoff]

  Jim, Ive had a ton of cooling problems and I HATE THEM. Most of what I do has been mentioned but I will go ahead and run down my list:

 1) If its not too much work or expense, I replace the common typical stock 3 core radiators with heavy duty 4 core as they usually fit in no problem...

 2) Of course, I install a new radiator pressure cap as its so cheap and easy. Of course all new belts and hoses.

 3) I flush and fill and use Distilled Water with 50/50 AFZ,,,,,,,Super Cool or Wetting Agent,,,,,,,,,new t stat if needed.

 4) A huge honkin auxiliary tranny cooler as that's a fairly easy and not too expensive job.

 5) Check fan clutch or of any aux electric fans check them.

6) If shes lugging hard up a hill I always shift down.

 Once I do all that she runs much cooler

 PS if an engine is timed too fast she heats up ya know

 John T

[Jim Stoltz]

I think the timing is a bit advanced - it runs on when I shut it off. I'll have to check the timing again.

[Wes Green]

You haven't mentioned it but do you have a fan shroud?  That will make a huge difference.  You definitely need a big trans cooler, get that hot fluid out of the radiator.  On the shroud, the fan should be half way in shroud.

[Jim Stoltz]

I do have a shroud - yes. There's no baffling up front though. It looks like there might have been. There's a small external trans cooler, but it supplements the radiator. The trans fluid still goes through it.

[Jim Stoltz]

So looking at it this morning. The external cooler looks like it was added later. It's teed into the trans lines that run into the radiator. So the hot transmission oil is still going in there. If I get a bigger external cooler (Flexalite makes a 24,500 GVWR unit) I can completely bypass the radiator, right?

Also, the engine oil runs through the radiator. I assume I can get an external cooler for that as well. Taking both hot oil sources out of the radiator should help I would think. But I don't want to compromise either oil by using too-small a cooler. Obviously the radiator is a water-to-air cooler and the external coolers are air-to-air.

[Jim Stoltz]

I also noticed that what I thought was the trans cooler is actually a power steering oil cooler. It was craptastically installed by slipping a 3/8" line over the fitting on the end of the disconnected high-pressure hose. Which explains the power steering fluid leak. If that blows it would ignite immediately. I need to remedy that. How important is a PS oil cooler? Can I just put it back to stock?