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Old 25th July 2008, 11:49   #16
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Quote:
Originally Posted by BaCkSeAtDrIVeR View Post
@Rehaan - why should a jeep have a thermostat?
The jeep, AFAICT, uses plain old cooling system. The fan, (again) AFAIK, always runs when the engine is running. The radiator / coolant fan on most modern cars start to run only when temperature goes above the threshold. Hence, there would not be a thermostat in a jeep's cooling system. Unless this jeep's cooling system was modified to included a thermostat.

Additionally, in old generation cooling systems, water is simply circulated, but not at high pressure as seen in most modern vehicles.


PS:- I am not suggesting a solution, but some pointers to trouble shooting.

2nd edit- saw that link to "what a thermostat really is" link by Rehaan. If that is what a thermostat does, what is the device whch switches on the fan called?
backseatdriver,

do not think the only purpose of a cooling system is to cool
down the engine. its job is to let the engine to warm up to normal
operating temperature and then maintain that temparature.
how does it do that?? with the thermostat, of course.

the thermostat will only let a miniscule amount of water to circulate
in the circuit when the engine is cold. this helps the engine in warming
up a lot quicker than it would with the water circulating. a cold engine
will suffer a lot more wear and tear, give more emissions and experience
more carbon deposits.

once the engine is up to the operating temperature, the thermostat
open and closes to regulate the water flow and in effect, the engine temperature.

thermostats have been very much a part of engine architecture since
water cooling has been in use. in jeeps too, the thermostat was very much present
in the very first iteration, Willys MB/GPW.

Use of coolant or antifreeze will only increase the spectrum between the
freezing point and boiling point of water. a antifreeze/water mixture will
freeze at a lower temperature and vaporize at a higher temperature compared
to plain water. it will NOT make the engine run hotter.

older engines used fans running off a pulley from the engine, some used
a thermoclutch, which varied the speed of the fan.
in engines equipped with electric fans, the fan will start operating around the
same time the thermostat starts opening. the fan is triggered through a relay,
which can get the signal to turn on/off the fan either from the
thermostat itself or the ECU.

cheers
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Old 25th July 2008, 12:21   #17
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Quote:
Originally Posted by nitrous View Post
Rehaan was explaining about the Thermostat valve. not the thermostat controlled radiator fan(which isn't present in samurai's jeep).

This thermostat valve is present to warm up an engine fast(so as to reduce engine wear). When the engine is cold, the thermostat valve is fully closed,so that the water in the water jackets of the engine circulate within the engine and get warm fast. Once,the engine gets warm, the thermostat valve now opens to let the coolant pass through the radiator,thus regular engine->radiator->engine coolant flow happens.
Correct and if the thermostat valve is always open, then the engine will take a long time to warm up. This would negate the FE.
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Old 25th July 2008, 12:38   #18
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Samurai,

As a fellow flatfender owner, if I could just give my 2 cents on this issue:

The cooling system of your Jeep is incredibly simple and inexpensive to overhaul. Keeping in mind that cooling system issues are the #1 cause for roadside breakdowns, I prefer to keep my vehicle's cooling system in top shape. Rather than guess what little part to replace, just do a complete overhaul to make it totally reliable. This is especially relevant since you recently purchased this used vehicle and do not know the details of the previous service history.

1. New radiator. (GTO suggested a good quality brand). Make sure it is a quality unit like the OEM or better. An extra row is a plus. Thick finned "local" units have very low efficiency and will not work. Efficiency is key.


2. New radiator cap. I would highly recommend a lower pressure cap as this will put less stress on your cooling system. I run a 7 psi cap.

3. Make sure all hoses are new. Try to use modern high quality hoses like you will find in your Suzuki, since these will last 5+ years. You will have to take the old hoses to a shop and try to match them up for a good fit. The low quality hand wrapped hoses typically sold for old Jeeps are very low quality and will only last one year or so.

4. Make sure all belts are new and tight.

5. Throw out the thermostat for now. Reason being, you want to make sure the cooling system has no blocks and is flowing fully. You can add it back later if needed, but if you do make sure you install a new one.

5. Get a brand new water pump that is OEM quality not local.

If you do all this your cooling should not be a problem. Since you fan and shroud look o.k. you should be in good shape. However if you still have a cooling problem, there there may be an internal issue with the engine, like the cylinder head.
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Old 25th July 2008, 13:11   #19
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Default Overheating problem in Jeep

Did you get in touch with the previous owner to understand if this problem was there before?
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Old 25th July 2008, 13:31   #20
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Dunno if this link is posted here before, but here it is:-

Automotive Cooling Systems -* A Short Course on How They Work

Going back to the first picture on this thread, (http://www.team-bhp.com/forum/attach...p-p6120956.jpg) - see the white tube from below the radiator cap going to the reservoir - this jeep has a "closed" cooling system described above.

The pics above do not disclose what runs the radiator fan. Is it the old always on type driven by a belt from the crank shaft? (my guess that this is the case). The belt would be under the shroud marked as NO. 9 in the image. And this jeep does not have a ECU. (and link above says that electric fans are operated by separate sensors - not the thermostat valve which controls the water flow).

And here is one more link to cooling systems troubleshooting:-

Steve Litt's Overheating Guide

Edit:- Samurai, most problems with the water pump are accompanied by water leaks FROM the pump - near the shaft which drives the pump. I am guessing from this picture -

http://www.team-bhp.com/forum/attach...p-_7235696.jpg -

center point of your fan and the water pump shaft are same. There would be water / coolant leaking from here. The cast iron "shroud" around the hoses is what is called the water pump. There would be "water pump kits" available in the market, which would contain new shafts, impellers, gaskets, and probably, bearings too. If poking around with the water pump, you can get one of these kits. Ought to cost around 1K - it is a guesstimate though.

And are you sure that the guage is accurate?

Last edited by BaCkSeAtDrIVeR : 25th July 2008 at 13:48.
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Old 25th July 2008, 13:54   #21
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Waitaminnut! Old diesel engines, those that have clocked up the kms and are running lower compression, have a tendency to heat up more than normal. Could this be the issue? Samu, maybe its time to get that compression test done?

While you are at it, check the condition of your head gasket too.
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Old 25th July 2008, 14:40   #22
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Quote:
Originally Posted by GTO View Post

While you are at it, check the condition of your head gasket too.
If the head gasket is gone, there will be oil in your raditor coolant and water in your engine sump.

Easy check, check the dipstick as well as the radiator water for water/oil traces respectively.
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Old 25th July 2008, 14:53   #23
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Quote:
Originally Posted by Jaggu View Post
samu: what is your exact problem which you are referring to by "overheating"?
It happens only under one situation, if I drive continously uphill for 20-30 minutes. It happened climbing the ghats towards Madikeri and then Choma Kunda. If I drive real hard in straight roads, no problem of heating at all. For example, I drove really hard from Madikeri to Manipal without break for 5 hours, not heating at all.
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Old 25th July 2008, 16:35   #24
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Quote:
Originally Posted by Samurai View Post
It happens only under one situation, if I drive continously uphill for 20-30 minutes. It happened climbing the ghats towards Madikeri and then Choma Kunda. If I drive real hard in straight roads, no problem of heating at all. For example, I drove really hard from Madikeri to Manipal without break for 5 hours, not heating at all.
Once, I tried to bunk class, saying "mummy, temperature". She replied, you are alive, and every living being will have a temperature, simply coz. he / it is alive!!! No offence meant, but that is to be expected.

On some ghat roads, (especially tirumala) there will be frequent ponds / reservoirs with water to deal with such vehicles. I guess this is normal. Especially with old vehicles - like GTO said.
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Old 25th July 2008, 17:48   #25
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Quote:
Originally Posted by samurai
It happens only under one situation, if I drive continously uphill for 20-30 minutes. It happened climbing the ghats towards Madikeri and then Choma Kunda. If I drive real hard in straight roads, no problem of heating at all. For example, I drove really hard from Madikeri to Manipal without break for 5 hours, not heating at all.
Sounds like air flow to radiator issue.
When you're driving hard on plains, there is wind gushing through the radiator fins .When you're climbing ghats, in theory, your speeds are lower and your engine is stressed more.
Solving the airflow by either using a pucca efficient fan shroud and/or adding an electric fan is what I would suggest. Purely trial and error.
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Old 26th July 2008, 03:15   #26
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Quote:
Originally Posted by Samurai View Post
It happens only under one situation, if I drive continously uphill for 20-30 minutes. It happened climbing the ghats towards Madikeri and then Choma Kunda. If I drive real hard in straight roads, no problem of heating at all. For example, I drove really hard from Madikeri to Manipal without break for 5 hours, not heating at all.
So is this "heating" or "over-heating" ?

Naturally there is more load on the engine when climbing and it will get hotter.
For example - when you are driving a car with the heater on in the cold winter, and you start acsending a hill, you immediately notice the blown air get warmer.

How high does the temp go? and increase of about 10-15*?
The question is - is it still within acceptable operational temperature for the engine (heating) or is it past that (over-heating) ?

cya
R
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Old 26th July 2008, 05:04   #27
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Rehaan has asked if this is really a problem at all. Other than asking a trusted expert in the business, can you quickly install a much better temperature gage and find out more accurately how hot you are? This gage would be handy to have in any case as would a very accurate voltmeter. Sometimes the two are sold as a unit.
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Old 26th July 2008, 10:04   #28
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I was told to make sure that temp doesn't go beyond 85C. Normally it stays at 80C, but when I start climbing some hilly terrain for 20-30 minutes, it starts hitting 90,95,100C. That's when I stop and get concerned.

Quote:
Originally Posted by DHABHAR.BEHRAM View Post
[b]Also, please check water in the radiator always. The XDP4.90 is a wet liner engine and any rise in temperature will lead to immediate seizure. I will give you service and lubrication instructions shortly.
After Mr.Dhabhar's warning I am being extra careful.
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Old 26th July 2008, 12:02   #29
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Samurai San, i guess it is ok to touch 100c once in a while. Generally seizures occur if the temp gauge prolongs in the 110C range.

Just ensure there is sufficient coolant in the radiator at all times.

I have seized a jeep by driving it without oil and water - infact did an offroad for 3 hour before i realised that there was no water in the raditor and oil in the engine sump. At that time my temp gauge was 120. The only time i've seen it so high. It generally stays between 70 to 110.

Also, as Dirtydan said, it might be better to change the temp gauge and the sensor to get a fairly accurate reading of the water temperature!
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Old 1st August 2008, 12:07   #30
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Dear Samurai - for your heating problem, first replace the radiator pressure cap. PLEASE USE ORIGINAL EQUIPMENT CAP ONLY. Also drain all the coolant and throw it away. Use normal tap water for experimentation (not well water). Then let me know.

Please give photographs of the radiator cap placed upside down as well as the radiator neck after removing the cap from it.

Best regards,

Behram Dhabhar
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