Hi have replaced the thermostat from 203 stock to 180. The temprature stood still, its not heating up at all..tested for 5 hours continues drive...there is no problem at all of heatup or air inside or leakeage...
When the engine coolant reaches boiling point it fills the bottle till max, it does not overflow.This is normal behaviour.
Problem is when it cools down it does not suck back from bottle. I need to fill radiator a little. bottle stays @ max. I changed the rad cap with brand new one, still same problem..
what could be issue. I am 1000% sure there is no leak @ all..
DO I NEED TO CHANGE RAD CAP TO A DIFFERENT PSI. or look for soemthing else.. stock is 21PSI CAP

 

May want to pressure test the system to see if you may (hopefully not) have a slight head gasket or block crack presurising the system with cylinder pressure. You will not see or find any leak of water out. You may be getting air in.

 

I haven't done pressure test, but drived car continuesly for 5 hours while stopping on for 10-30 minutes with A/C ON. the needle will stay in normal position. check the upper hose it has normal pressure.
we have 45+ degree centigrade now a days. real hot. it just started after changing the thermostat form 203 to 180. tested while keeping rad cap off & running engine for 1+ hour, it does not boil or havent seen single air bubble. I am sure there is no leak or air inside. its just 35K miles only.

any ideas appriciated

 

If it isn't flowing over the overflow tank, don't worry about it. The system will take and replace what it wants when it wants if the hose is attached.

IndyDurango

 

the good thing is that its not overflowing at all... actually I checked today morning before starting engine..it was low in radiator and I top it up full.after driving & while engine running I checked again & coolant was pushed in bottle. will check again when leaving from office after 8 hours. if it got the same level in bottle as it was in morning before starting.
But what if bottle gets back same level as in mornig before starting and radiator again needs some coolant?
just a thought
is it possible that puting a low temp thermostat, is not making that pressure which required to create enough vaccuum to suck all of the coolant.?
and as this tstat opens earlier will also close earlier? will not allow to suck all that coolant which is pushed by water pump?
should I go for different pressure tstat?
is there any relation between tstat temp & radiator cap pressure setting? (e.g: 203 use 21PSI / 195 use 18PSI and180 use 16 PSI).

thanks for your replies & efforts

 

The overflow is very active. I used to think mine never even worked. That was until I swapped it for a very small, but pretty, chrome tank. It is WAY more active than I ever imagined.

With 2 gallons of coolant in the system, the little in the overflow isn't hurting anything. Again, if all is well, stat is working and not stuck, hoses are good, not loosing any to boil over, even if cap is welded shut, the system will do what it wants to do and add/draw coolant as needed.

Don't worry about it and find something else more worthy of the extended efforts.

JMHO however that is exactly what I would do/am doing on my Durango. And I think itis getting along just fine.

HTH,

IndyDurango

 

it is fine as such. BTW today temp is 47+ centigrade, and temp raised till almost 195, becos i stuck in traffic for 30 minutes & it wasn't in nuetral, else was in drive for 30 minutes. when got out of it drived for 3 minutes it came back to normal & i checked there was no overflow..
I will keep it closed for 3-4 days & will motitor & check after 3-4 days the coolant level in rad. if it got same a little loose as I imagine daily, then its normal,,,no lose no gain but will never fill till neck. BTW is there any site of data to check which thermostat temp uses which PSI cap?

a really appriciate your help

thanks & best regards

 

I switched to a 180 degreee thermostat four years ago without a single problem. I never noticed my overflow purging,
FF

 

@ff are you using stock pressure cap 21 PSI?
its not purging the overflow. its just strange that If I fill radiator till neck ->Drive-> pressure pushes coolant in overflow->cool down engine->checked overflow. the coolant got sucked from bottle, but not same amount as pushed in bottle.
checked radiator & its a little low in coolant.

 

I am using the stock cap,
FF