Bad thermostat? 98 v70

skloon · Post by **skloon** » 01 Jan 2017, 23:30

Driving in the city the temperature seems okay once I hit the highway the Guage drops down almost to the bottom and I get very little heat, tonight is -27 and the Guage will hit normal when idling after 20 minutes but when I get going drops to the bottom has coolant so I would guess a bad thermostat but don't quite understand what is going on

difflock54 · Post by **difflock54** » 02 Jan 2017, 01:04

From your description one wonders if there is a thermostat currently fitted at all???
Or maybe it is jammed fully open.
Does the radiator fan come on after the long idle period as would be expected when the engine gets hotter.
If the fan is permanently on, that would result in the engine running cooler than normal also.

Post by **erikv11** » 02 Jan 2017, 01:32

Fits exactly the symptoms of a bad (stuck open) thermostat.

Post by **cn90** » 02 Jan 2017, 09:29

1+,

Stuck open.

My experience with tstat is that: after 50K, they are "OK", i.e., somewhat OK but not as "hot" as factory.
Then at 70K, they are somewhat "cool".

Anyway, I routinely replace tstat every 70K or so, it is $15 well-spent. Also a bad tstat affects fuel mileage, so you save money with a new tstat.

beigg · Post by **beigg** » 02 Jan 2017, 17:09

cn90 wrote:1+,

Stuck open.

My experience with tstat is that: after 50K, they are "OK", i.e., somewhat OK but not as "hot" as factory.
Then at 70K, they are somewhat "cool".

Anyway, I routinely replace tstat every 70K or so, it is $15 well-spent. Also a bad tstat affects fuel mileage, so you save money with a new tstat.

unless it's an '06+ S60 then it's $100+ ...

Post by **cn90** » 02 Jan 2017, 22:49

beigg wrote:...unless it's an '06+ S60 then it's $100+ ...

I know, I just replaced the tstat in my 2005 XC90 2.5T with 105K.

The whole assembly costs $95 b/c it is sold as a unit, which includes tstat + ECT + upper and lower housings.
The stat itself is about $15.
ECT is about $50.
So, it was not a bad deal b/c ECT goes out at 100K or so anyway.

skloon · Post by **skloon** » 03 Jan 2017, 00:58

Worst thing is I have two new thermostats on the shelf at home- I am away- just got in and the temp shows -34 I plan to hibernate for a bit

Post by **erikv11** » 03 Jan 2017, 07:58

cn90 wrote:
beigg wrote:...unless it's an '06+ S60 then it's $100+ ...
I know, I just replaced the tstat in my 2005 XC90 2.5T with 105K.

The whole assembly costs $95 b/c it is sold as a unit, which includes tstat + ECT + upper and lower housings.
The stat itself is about $15.
ECT is about $50.
So, it was not a bad deal b/c ECT goes out at 100K or so anyway.

(1) Unfortunately the cost for that repair is still $100. It's not about what it should cost, or what it's worth, or what you would like to pay, but what it actually costs.

(2) Not even close to every ECT goes out at 100k. Look at the cars in my signature - not one has needed an ECT replacement yet. Yes they go bad sometimes, probably I have been lucky, but no need to lead people astray about the quality of that part.

Post by **cn90** » 03 Jan 2017, 08:34

Erik,

I like to infer this, infer that, but I am used to your comments by now.

People are smart, they form their own opinions. I don't lead anyone astray as you suggested.
I only state my opinions and my experience (it does not have to be correct) and that is it, people form their own.

I have gone through 2 ECTs in the 1998 V70, S70. They fail like clockwork, around 100K or so.
Forums have tons of ECT posts, I don't need to repeat.

What I said above pertains to 2.5T (fitted in S60, some S80 and some XC90) with tstat assembly sold as a unit.
In the 2.5T, I wish I can replace ONLY the tstat, which normally costs $15 or so.
That is not the case, Volvo forces people to buy the whole assembly for the 2.5T engine, this way you have to replace not only the tstat but also the ECT and the housings.
Kind of a waste.

But my practical side told me:
1. I don't have a choice, so I spent $95 for the Wahler assembly for my 2005 XC90 2.5T.
2. Do I like it? No I don't, but I take the opportunity to replace the ECT too. And I should be good for another 100K.
3. Do I sweat over this? No, I am practical, I get it done and move on, plus I didn't have a choice to buy only the tstat.

I don't want to defend for Volvo, but my theory is that Volvo knows from the P80 series, they often replaced the tstat, then ECT later.
The field experience was provided to Volvo HQ by local dealer mechanics.
So, they said "what the heck, make a combo unit with everything included and done with".

And yes, you are lucky with your ECTs.

Post by **oragex** » 03 Jan 2017, 09:14

erikv11 wrote:Fits exactly the symptoms of a bad (stuck open) thermostat.

was going to use the same words. highways gets lots of cold air on the radiator. since the coolant flows continuously it really gets cooled down, compared to city driving/idling

the easiest thermostat check is start with cold engine, idle for a minute, check the upper rad hose for warm in the middle --->> t-stat stuck open (it only fails open on these cars)

it doesn't matter if the temp needle stays at 12h, the stat can still be stuck more or less open