When I use my 1978 Dodge van, (318 cubic inch engine automatic transmission) the longest distance I ever drive round trip is about 14 miles to a veterinary supply store for dog food.The other two places I drive to average (round trip) are 8 miles (tobacco store) and 6 miles (food store).Which thermostat for my van will allow the lowest radiator pressure? I don't know what the old thermostat pressure rating in my van is now, I would have to take the old thermostat out and have a look at it. cuhulin
The thermostat only controls how long the engine stays in warm up mode or how 'cold' it can run. Once the engine is up to proper operating temperature, the thermostat stays open usually. Unless it is say -40 outside...
If the thermostat was opening and closing, you would see your temperature gauge fluctuating up and down which they don't do.
If you want a lower pressure, you can change the pressure cap to a lower number. This will mean your rad will puke out coolant at a lower temperature into the overflow bottle and if all things are working properly, suck it back when it cools down.
The lower pressure lowers the boiling point.
Mike
86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00 'New' frame in the works for '08. Some Canadian Bush Trip and Build Photos:
maybe with winter coming it would be best to put in a 195 thermostat. the thermostat regulates the temperature. the rad cap regulates the pressure. I run a 195 winter and summer. I think some stores only stock the 195.
The thermostat should open all the way. That would be an indication of a faulty cooling system. The cooling capacity, if the system is working properly, should be able to maintain the thermostat temp (180F or 190F or 195F or whatever) even if you take the car to Death Valley and the ambient air temperature is 135F. In order for it to maintain the same temp when the air is 80F as it does at 135F the thermostat has to throttle some of the flow (i. e. it closes a little). When you get down to -40F the thermostat might stay all the way closed if the engine loses enough heat thru other surfaces.
It actually does just that. When you start to climb a hill the engine may increase in temp by a a little (say half a degree) and the thermostat responds by opening a little farther. Coasting down the other side of the hill will start to cool the engine and the thermostat will respond by closing a little. If you had an accurate enough temperature readout (digital that reads 0.1F increments) you would see the small fluctuations.
-jim
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For short distances, you can just loosen the radiator cap so that it holds no pressure. If the van is not overheating for some other reason, this will take the pressure off the radiator and leaky hoses and get you down the road a bit.
In fact, in some cases you can go a LONG way this way.
Well, I for one have never owned one of these mythical vehicles you talk about. Mine all warm up to 195 fairly fast so I have heat and after that most run about 205-210F. Yes, I have used infrared to verify the thermostats on several vehicles, even on a 318.
This is noted when I drive in the summer and then in the Canadian winters. At sub zero temps, my temperature gauges all stay low or at the 195 the thermostat is forcing the engine to run at or just out of the bottom or 'cold' range. (Yes, the engine gets forced to the t-stat's temp, if I use a colder t-stat, the gauge is lower and the inside heat is radically lower in the winter)
Then when I drive in summer, they come up fast to that 195 point and then 'rise' up to the center of the gauge for the rest of the trip.
My engines all run at the margin the rad is designed for, no extra. They even have extra fans that come on if I exceed that marginal cooling the main rad fan can pull by say putting on an AC pump or if it just plain gets up into the boil range, say if I am in 4 wheel low in 100F weather.
Mike
86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00 'New' frame in the works for '08. Some Canadian Bush Trip and Build Photos:
That little approximately quarter inch diameter corrosion rust hole in the top right corner of the timing chain case cover of my 1978 Dodge van, the hole is on top of the timing chain case cover right up there very near the cylinder head.I finially have a chance to try and fix that with some J B Weld.I have a small hand held steam cleaner, like the kind you have probally seen in the stores or tv commercials.I am going to try and steam clean the area and then after it dries off real good, I will apply some J B Weld.I never thought about looseing the radiator cap to help relieve the pressure while I am driving.I do know enough about removing a radiator cap when the coolant is hot, I learned that the hard way about fifty years ago.I am concerned the radiator pressure might blow the J B Weld off of there.As soon as I can get around to it, I will check the local area auto junk yards for a good timing chain case cover for my van.My sister (she and her hubby live in another part of town) has been taking me wherever in town I need to go. I am keeping my eyes open for a good older model ex-ambulance vehicle (cube van) I can buy at a good price.I like big old vehicles with lots of space. cuhulin
You are describing a vehicle with inadequate cooling system. And yes your thermostat is likely to be wide open.
I was talking about cars with adequate cooling capacity (that description fits most cars on the road). On a hot day in stop and go traffic the engine will start to get a little warmer and the thermostat will open a little in response and the cooling fans also come on and the net result is pretty close to normal gauge temperature is maintained (it will be so close to normal most people with a gauge don't notice any temp change). That normal temp will be pretty much the same on these cars in winter or summer. Although if it ever does get down to
-40F outside the gauge may drop in temp a wee bit below normal since most manufacturers consider that extreme temperature to be outside the normal expected ambient temp range. But I would say at around -10F most cars warm up to normal.
-jim
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If you watch the CTS on a scanner on test drives you will see that cars will act differently. Some cars will have a rock steady temperature. Some cars will have a temperature fluctuation of a few degrees.
Yes, where the sensor is located will make some difference in what you see. but whether you observe fluctuations or not in order for the cooling system to have some reserve capacity it must be designed so that the thermostat controls the flow in order to maintain normal operating temp. On most cars at highway speed there is enough airflow thru the radiator that fans contribute nothing. If the outside temp is 70 degrees and the thermostat is wide open then there is no reserve capacity for when the air temp goes higher.
-jim
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"HLS" wrote in news:bCTwk.12428$ snipped-for-privacy@flpi147.ffdc.sbc.com:
If it has a cross flow rad it is usually not poss to loosen the rad cap as it will leak as the flow throws water against it. if it is a top flow rad you can run with the cap loose all the time as long as there is no overheat situation. I run all my old top flows with no pressure with no problems. (of course I don`t use them in 100 degree heat either.) on the cross flows I use a 4 or 7 lb cap. KB
Just get a low pressure cap that is better than leaving the cap loose.
The trick to making the JB weld repair last is to get the stuff to balloon out on the inside of the hole. Take a nail or something similar and get some of the epoxy on the inside surfaces of the hole.. Then make a patch by smearing the rest of the epoxy onto a small square of denim or canvas cloth and press that on over the hole and allow to set. The idea is that the epoxy will expand slightly as it is pushed thru the hole and after it is set then pressure won't be able to push it back thru the hole.
-jim
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About this repair you have in mind, the JB weld. I like the stuff but I think you need to attack the hole or crack with something other than steam. You say it is rusty...then use acid or Naval jelly to get rid of the rust. Steam will not remove the rust. You may also be able to scrape the area clean enough with your pocket knife to give the epoxy fresh metal to bond to.
Of course it will be best to replace the timing cover. Replace the front seal. You will have to remove the vibration dampener. Notice the grove cut into the dampener by the seal. If very deep then there is a repair front seal with a chrome collar that gets put over the end of the dampener. Do it once and you're ready to go.
Have had a lot of these vihicles come in in very weak running condition... because the mass market, giant, super chain parts stores carry the worst carburators. Most of them we see all start with a basic carb rebuild and they run for years after that.
The radiator has verticle tubes, a top tank and a bottom tank.The old worn out REX (brand name) radiator cap says 15 - 18 LBS.The bottom tank has a petcock valve for draining the radiator fluid and there are two places on the bottom tank where the automatic transmission lines are connected to the radiator.I reckon it is a down flow, or top flow radiator.
The little steamer gadget seems to work ok but it is slow.I think I have an old quart can of engine degreaser stuff around here somewhere.I am going to see if I can speed things up with that.
I know about rust, rust never sleeps.I think the best way I can remove the rust from that hole area is with a little round wire brush or toothbtush wire brush.Because the hole is in a hard to reach area. cuhulin
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