good morning everyone and thank you for your help in advance. I have the 2.5 turbo model and the temp is only reading 1/4 way up the scale for the last month. I tried a serch but more where for the standard s60 and there are some differences like you cannot just swap a thermostat because volvo only sells a complete houseing for the turbo model, i do not see why. oh well I did replace the housing so the thermostat and the sensor next to it are new but it is still running cold. the cooling fan is not coming on so that is not the issue, i think there is another sensor i am missing near the airbox??? (so i hear, but no clue)

any ideas

Peace and Love Ron

 

You replaced both t-stat air temp sensor and the gauge still doesn't go to middle?

how is temperature in the vehicle if you put the heat to max, does it blow hot air?

 

yes we get heat but i would not call it the normal volvo get me out of this car heat like the 740,s or the 240's. but it is not cold either it is a good warm not hot i would say. if that helps at all.

Peace and Love Ron

 

when u replaced the thermostat housing, did u separated into 2 pieces to installed? or did u installed as 1 unit? in other words, did u opened the screws on the thermostat? is the lower coolant hose always cold?

 

normally at max the heat is pretty hot, not burning hot but hot. I would guess either the thermostat has a lower opening temp either it doesn't fully close. the t-stat is the only part in the system that can control the temperature.

near the airbox there is the maf sensor, but is not related with the coolant temp.

is mpg in the range or lower?

finally, a bad t-stat causing the coolant, and consequently the engine temp to stay lower than normal, will cause inefficient fuel burning, and will mess (clog) the oxygen sensors in the long term.

 

the temp was running lower before and after the thermostat was replaced so it was like that made no difference. the gas milage remanins at 21-22 mpg which is in the normal for what my wife does in this car normally in the winter. I did have to open the houseing because the bottom bolt was stripped i found so i openned it and replaced the t stat and gasket, used a deep well impact on the sensor and r and r ed it also. I have not checked the bottom rad. hose. the car seems to run fine but has a slight rough idle that ribrights the steering wheel. the check engine light has come on 2 times. first was the MAF i replaced it second was sometime about running to cold so now i see the gauge (this is my wifes car , i ride a motorcycle daily so i do not "see" everything as it happens)

Peace and Love Ron

 

just thinking i do not recall the temp being so cold till after i replaced the MAF, could this be causing it? a wrong one or a bad one? i have not gotten a code for a MAF again but.... just a thought.

 

there shouldn't be other reasons for running too cold other than an issue with the t-stat (considering the temp sensor is fine).

I would point to the way the t-stat was placed inside it's housing. Sometimes the t-stat has a small hole for air bleeding that needs to stay in a specific position. I would make 100% sure the t-stat is exactly properly seated inside the housing. I would also make sure there is no air in the system, by pumping the front hose with the reservoir cap removed.

The maf sensor reads about the air getting into the engine, it's related to the air/fuel ratio mixture or something like that

 

is there a way to test the temp sensor with a ohm meter? maybe i got a bad one. when i openned the houseing i made sure to make note of the position to place it back as it was removed. now i can do the pump the hose with the reservoir cap off as i have not tryied that. and again thank you

Peace and Love Ron

 

u r talking multiple problems here MAF, CHECK ENGINE LIGHT, TEMP. GAUAGE... u need to isolate & fix the problem one by one. There is a reason why volvo has the thermostat housing with the thermostat in 1 piece. cuz they went into problems that when installing the thermostat, the thermostat not sitting @ the right position. So the thermostat not performing like it should. I would go back & recheck if the thermostat is working first. check the lower rad hose after a long drive & c if it is cold. if so, the thermostat may not b working right

 

ok problem solved, here is the problem and solution. if you have to open the housing and swap thermostats out as i did due to a stripped houseing bolt the thermostat must be "set" to the "new" houseing. take the new thermostat andthe outer housing cover that the hose connects to and compress the two together thill the thermostat seals to the houseing and is completly flush. when i tool it back apart there was still a 1/4 inch gap even thou the pin on the thermostat was in the hole and the "feet "where in the "feet" holders with the bleeder hole at the top. I did this and was suprised that that was all it needed to seat. I reinstalled everything and cranked it up and in about 2 mins the gauge was at 1/2 ,for the first time in 3 months.

crazy, but i guess that is why they say do not open it just intall it. I hope this helps save someone else the time and trouble.

Peace and Love Ron

 

Thanks for the feedback, I will have to do the same soon,

Question, did you use some sealant between the two casing parts ?

 

no it came with a metal gasket that i reused both times with no signs of a leak, hope it helps. I used the bolts to hold the gasket to the hose half of the houseing or i guess you could use some form a gasket sealant to hold the gasket in place on the block side and let it dry some then install to keep it in line for the bolts.

Peace and Love Ron

 

great, thanks