Around town runs cool but not after freeway driving

Rusty Scout

Rusty Scout

Member
Scout II 345 with a/c

the symptom is after just 10 miles of freeway driving and then getting off the freeway and say stopping and idling at a red light the temp goes way up. Temp stays normal on the freeway. If I get back on the freeway the ram air cools it down to normal again. I don't think this is a normal condition.

My diagnosis is plugged radiator with cracks.

Also I am losing a lot water. I am guessing in the form of vapor out the cracks at highway speeds. I am running a 7lb cap because the radiator is old and tired. I am using a lot of water but no obvious leaks, drips or steam in the exhaust. The fan clutch seems ok too. Using a rs370-180. Its got a fan shroud too.

I flushed the system yesterday using prestone super flush for 3 hours of driving and idling. I drained the block and radiator first. Today the old hoses are getting replaced and the old radiator is getting replaced with a fresh 3 row. Also going to replace the 180 with a 195 rs370 tstat.
 
Yep! If it won't pressurize, it won't cool! Comes with the turf and time between maintenance!

I just had a brain fart...if ya filled the rig with water and barr's leak, it would plug up all the rust holes in the body! Don't lock yoreself inside while doing that though, teddy kennedy might come back to life!
 
The other thought I have floating around is about the water pump. It was replaced with a napa stamped steel impeller pump not long before my around town cool but not after getting off the freeway symptom began. What is the symptom of a water pump with improper impeller clearance issues(too much clearance)?? I would think hot around town, right?
 
rusty Scout said:
the other thought I have floating around is about the water pump. It was replaced with a napa stamped steel impeller pump not long before my around town cool but not after getting off the freeway symptom began. What is the symptom of a water pump with improper impeller clearance issues(too much clearance)?? I would think hot around town, right?
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Only one way to know what the impeller clearance is...measure it! And even a cast impeller pump could have the wrong clearance.

All this conjecture about "stamped vs. Cast" impeller is total bs/IH urban myth. We've beat that horse to death around here!
 
I don't care if it is stamped or cast. I just was wondering if there was a tell tail sign that an impeller to pump housing issue was going on here. However, it seems to me that a low flowing pump around town is not whats going on here. If anything the "cooling module" is flowing too much cause the gauge reads low around town and not normal until on the freeway. Of course this is interpolating the stock gauge after years of comparing it to a mechanical gauge.

Anyway time to load the wagon and worry about the horses later. The hoses were getting close to 8 yrs old and that rad was cobbed together from 3 old rads dating back to the east palo alto days of jim marsh and the original anything Scout. Onward now that I got good weather for the first time in months.
 
Well it looks like I am doing the right thing and I will share some words about my question re impeller worries that I got from my ihc guru:

"there is no "symptom" of an incorrect impeller clearance issue! If...all "normal" things have been corrected/verified, and you stiill have an overheat condition, then the clearance is the last thing to check as it's the far least likely cause of cooling issues.

Any vehicle when run hard at high engine rpm with mucho ram air through the radiator, will show a temp increase when air flow diminishes because of lower fan rpm, lower impeller rpm, and lack of ram air at low road speed. Therefore the engine temp goes up before it comes down! And anywhere on that horizontal bar on the oem gauge is considered the "normal" range. That bar represents a nominal 170*f on the left end and 210*f on the high end. That is a perfectly normal temp range for these rigs with a 180>195 tstat. A Scout II has a 20% smaller radiator compared to a pickall, therefore it's cooling capacity is "less" and it takes longer to recover (reject the excess heat created from a hard run).

I think once you have your cooling system service project completed, you will find things are ok.

All the cooling system issues that folks post about on this stuff is created by their changing out all the oem stuff and adding all the workarounds! That...and total lack of periodic maintenance in the past, that must be corrected before moving forward."




so after my work is completed on this system overhaul I will write a little follow up in the case that someone else was thinking along my lines.

Next ponder: I wonder what the the life expectancy is on 31 year old water tubes and orings on a sv motor that has been fairly well maintained with around 250k miles on it? Anyone consider the water pipes service items with a finite lifespan such as hoses and radiators? Also are water tubes unique to ihc sv engines?
 
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Yes, the hard plumbed water tubes used on the IH motors are unique to IH design.

If the tube flanges where the "o" rings seat are not rotted, and the tubes are not perforated from corrosion, they have an indefinite life span. Since you currently have the tubes off your pickup motor, take a look at those for comparison regarding the condition.

If the water tube "o" rings are not leaking currently, then they won't leak any time soon! If you were to remove the tubes now, I promise they will look like hell and you will find corrosion, but as long as ya don't disturb 'em, they won't leak.

If you do remove 'em (and do the same on the water pump housing on the engine you are building), then the seats in the water pump housing must be clean and have no roughness where the new "o" rings seat. When re-installing the tubes with the new "o" rings, I always lubricate the rubber with a film of hylomar as insurance.

You have new "o" rings in that gasket set for the 304 for comparison. Those are nothing special and a common industrial size. We have those in stock separately also at ihon, all four are the same size.

The actual water tubes for a 152 (single) 266, 304, 345 interchange. Water tubes for the ic 196 (single) and ic 392 are likewise unique to the engine app. edit: I May be incorrect regarding the length differences in the short deck and tall deck water tubes, I need to verify this when I have time!!! I've now verified part number info and corrected this post.

Bottom line...if the water tubes on the Scout II are not leaking now, don't disturb 'em!
 
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Well before I switched over to this forum the other one had me thinking I should run the rs 370-180 stat. Seems like my so called cooling system "abnormalities" started when I began running the rs370-180. Prior to that I was running regular 180 thermostats.

Tonight I put this stat in a pot of water on the stove and found that it began to open at 150, 40% open at 160, 80% open at 170 and 100% at 180. Now I see why my gauge was reading low around town (needle was always about half way to the normal op temp range segment of the gauge unless I got stuck in traffic or got on the freeway for a while).


I got my 195 stat last week from Jeff and that should bring operating temps back to where they should be.

As a side note on the other symptom appeared (mysterious water loss/no obvious leak) and got my attention on the last major road trip(nov08) which was a nonstop run from the bay area to anza borrego about 600 miles with a couple of slow socal traffic doses. Next morning we continued on to go watch the baja 1000 trophy trucks north of san felipe baja. Got about 5 miles down the road and I was going man this thing aint warming up whats up with that. Pulled to the side of the road and found I was a little low on water. Had to add close to 2.5 gals of water after the hot air was purged from the system and the engine cooled off enough. Got to el centro and added a container of anti rust and big bottle of heavy duty bars leak cause we did not want to miss the racers(dumbass move). Did not lose any more water on that trip but who knows what that snake oil did to the old tired radiator or what driving corvair style in the desert did to the engine. :incazzato: seemed to be fine though after that quick fix although that night we did got lost in the middle of nowhere on unmarked back roads (ambiguous map and no gps~never again) heading north for guadalupe canyon hot springs skirting laguna salada from the south from mex5. We got back on track though with the stars, a hand held compass and the glow of mexicali 60 miles in the distance behind some mountains. Only did about 40 miles of lost driving. White knuckle driving in dangerous mex drug mafia territory at night across a lakebed(known for swallowing up cars in hidden wet spots) and then miles and miles of washes and deep ass sand ruts that some other baja race had torn up in recent times in a 30yr old truck with over 200k. It was a great adventure only because we lived to tell about it.

Since then on every desert road trip the most I've let it slip was about a .5 gal after the 6-8 hour runs on the highway to get there.
 
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Folks over here are big on the rs-370 design also. Model year 1980 engines with the re-vamped water neck and thermo housing (a major eop cost reduction move) are the only sv's that don't call for the balanced flow t-stat.
 
scoutboy74 said:
folks over here are big on the rs-370 design also. Model year 1980 engines with the re-vamped water neck and thermo housing (a major eop cost reduction move) are the only sv's that don't call for the balanced flow t-stat.
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Actually, the rs-pattern "balanced flow" tstat works much better in a "conventional" bypass cooling system such as the bastard '80 model sv crap. That is why all the performance engine component sites pimp 'em so heavily...at off-the-wall prices.

They will replace any typical poppet-type thermostat as long as the can doesn't interfere with any surrounding casting. They are manufactured in several different flange diameters along with corresponding can diameters, the IH app (rs 370) is one of the larger designs and is also used in many other engine applications.
 
rusty Scout said:
since then on every desert road trip the most I've let it slip was about a .5 gal after the 6-8 hour runs on the highway to get there.
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Well, I do not know where the water is going, but based on my limited experience that is too much fluid loss.

I would put 1" - 2" of water in the resorvoir once or twice a year (392 in a t/a). I drive to death valley (500 miles each way) without adding water -- atually, I am probably over confident -- I sometimes did not even raise the hood...

Possibilities are cracked cylinder head(s); cracks in the radiator (along the seams at the tanks) or loose hose clamps...

Your 180 thermostat seems to be working fine to me...
 
Somethings leaking but not obvious. The front of the block had some evidence on it pointing to radiator. I am hoping hoses, radiator, and cap will do the trick before I do the 345. Engine stand full at the moment.

Got a new rad last year from a guy on craigslist for 200 bucks nib sittin in his garage. Sold his Scout before he used it.
 
There is only one way to determine cooling system liquid loss. That is to pressure test the system, both at ambient and at operating temperature.

You can be loosing coolant as a vapor and never see it or be able to find any evidence of liquid tracking. Once the coolant mixture escapes to atmospheric pressure, the "water" component flashes immediately, leaving a trace of glycol which is soon cooked off from heat also though it May leave a fluorescing stain of sorts. If the leak is in an inaccessible location you will never see liquid evidence. Such a a pinhole in the middle row of a three core/pass radiator.

Same for a cracked cylinder head, the leak May occur only at initial startup and then actually close up due to expansion.

A head gasket seep May show up as a coolant stain to the outside, but most coolant leaks in the head gasket area are across the water port to a head bolt/stud or across the fire ring into the combustion chamber. In that case a "combustion leak" test is made of the coolant in the radiator while the engine is running, and a leak of that sort will show up as an increase in cooling system pressure causing the radiator cap to bleed not because of temperature but because of combustion pressure entering the cooling system.

If the cap is not holding pressure (and many of the aftermarket caps in the "value price range" are shit such as the "motorad" brand), the constant movement in and out of the burp bottle (because the caps do not function properly) which is open to the atmosphere allows a given amount of the water component to vaporize off also to the atmosphere, resulting in a perceived loss of liquid over time.

No matter how the oem May refer to the cooling system as a "sealed" system, they are not. The overflow/burp bottle on the IH and most convention coolant recovery systems are all vented to the atmosphere. On top of that, the vast majority of the oem plastic burp bottles found on these rigs that are original will not even hold coolant due to cracks and holes. The system constantly is burping and recovering from the bottle, if the liquid level inside the burp bottle drops below the level of the dip tube, then what is recovered is air.
 
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2 questions

holy smokes it takes me a long time to do anything on these trucks. Especially when you are going that extra mile doing stuff like painting the fan shroud, thermostat housing and positioning the heater valve so it does not interfere with spark plug wires, old a/c lines, air injection hoses and stove pipes.

Everything is finally done except adding the green stuff. Probably have a new layer of rust going in the water jacket which did not clean up as well as I hoped. I did flush the jackets as well as I could with the nozzle on the garden hose until nothing but clean water came out. This was after a few days since it was flushed and drained with the prestone super flush. I replaced the steel pipe plugs with hex head brass pipe plugs.

??? should I add prestone anti rust or does that qualify as snake oil ?

also not really thrilled with the position of the fan in the shroud . it sits low in the opening . I did polyurethane stock height body mounts a few years ago .

??? Could that be it in addition to worn out original engine mounts allowing the engine to sit a little lower than it should up front?

The rear tranny mount is an rpt replacement.
:confused5:
 
I don't use anything in the cooling systems I service other than plain old glycol-base anti-freeze mixed 50/50.

When you use the cleaning solutions that are available to the consumer, they bring some of the metal back to bright condition, but as soon as exposed to air the surface film of rust begins again, that is not a concern to me as the inhibitor chemicals contained in the fresh anti-freeze will handle it.

The poly body mounts are probably about 1/2" thicker than oem and those don't collapse at all over time! And your front engine mounts are prolly somewhat collapsed also if you haven't replaced 'em.

The easiest thing to do is simply "slot" the shroud mounting points and lower it slightly. You can gain about 1/4" by doing that, and it doesn't drop it so far that ya end up with an "air leak" at the top where the shroud meets the top edge of the core. If you do have an air leak, then use foam tape to seal the gap just like Nissan/toyota/honda do!
 
Well now I have a reason to justify buying some rpt engine mounts from Jeff. Got to position than fan just right.

Got it all buttoned up and filled. I took it out for a shakedown on my test track: the richmond-san rafael bridge. The temp reading on the gauge looks like it should and does not budge. After a high speed 10 mile run I pulled over and watched the gauge stay right where it should.
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I was patting myself on the back. Got back on the road to go home and I started smelling coolant. Then the gauge started to climb and then I noticed the cloud of steam behind me. The upper hose blew off the water neck. But that's another story. The moral there was to warm up the Scout at home and then recheck the hoses for tightness again before road testing. And follow dr. Mayben's instructions 100% and roadtest it with only water so if there is a catastrophe you don't lose $30 worth of coolant. Just another bone head adventure. All is well though once again.

I think I May take the dremel tool to the shroud where it makes contact with the upper hose and make some proper clearance there. I was concerned about that and did not put the upper hose on the thermostat housing neck far enough. Doh


next I plan to devise a red neck engine coolant dialysis machine to manage the rust levels.
 
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