[Engine] Driving without a thermostat ... any side effects?

[Miswick]

Why does Berlingo Gent appear under my name now? And I'm not even a gent. Assumptions eh? Or just a forum thing?

[Miswick]

Good result in the end and thanks for sharing.

Better in than out with a thermostat !! ...

With a thermostat removed the coolant flow around the block is affected negatively since a large part of it is permanently flowing through the radiator instead of doing its job of removing heat from the engine, those further flung parts of the engine receive less coolant flow and less cooling effect leading to localised hot spots and potential for failure.

Cheers geoff, but isn't the job of ... the thing I've banned myself from thinking about ... to heat up the engine as quickly as possible to optimum temperature, and to open, for movement through the rad, when it's reached that temp, so that it doesn't go any higher. Maybe I'm not fully understanding .... is what you're suggesting, that even without a t-stat, an engine will heat up anyway, and when it does, the cooling process isn't effective enough to then keep it within normal range?

[geoff]

[/quote]

Cheers geoff, but isn't the job ... to heat up the engine as quickly as possible to optimum temperature, and to open, for movement through the rad, when it's reached that temp, so that it doesn't go any higher.

Maybe I'm not fully understanding .... is what you're suggesting, that even without a t-stat, an engine will heat up anyway, and when it does, the cooling process isn't effective enough to then keep it within normal range?
[/quote]

1/ Put simply yes

2/ a, It will heat up anyway

b, the system isn't effective enough to keep ALL of the engine within normal range

A missing thermostat allows the majority of the coolant flow to be diverted through the radiator with only the remaining flow going through the engine.

Eventually the remaining flow through the engine reaches heat saturation and can allow SOME areas of the engine to overheat.

What you have with a thermostat isn't a binary situation for it is continually cycling open and partially closed in response to engine temperature providing for more or less cooling as required to maintain the optimum temperature.

When partially closed more coolant is forced to flow around the engine to cool those far flung corners that would otherwise overheat.

Whilst the radiator is more than effective at cooling what goes through it the key point is that with a missing stat the majority of the coolant will be flowing through the radiator and not the engine where the heat is being generated.

I'm probably making a hash of explaining but be assured that whilst an engine can and will run without a stat doing so long term will be detrimental to the engine and ultimately the wallet.

[Miswick]

Thanks for your patience geoff. I think I'm getting you now ... relevant words being ... 'forced' to flow in a particular way.

So, it also acts as some kind of 'regulator' to control the pace of the flow, allowing the exchange of heat/cold to work more efficiently as well as directing the flow to areas where it might not otherwise go.

It concurs with a remark I heard on the phone – the one dissenting voice – a Citroen mechanic answering a question about the lack of a thermostat keeping the engine cooler, to which his reply was 'not necessarily' before he got interrupted. The rest could have been interesting ...

Well, it makes me feel better having it back in place anyway, and it's staying there this time.
I hope it doesn't ever 'slack off' on the job again and throw another hissy fit.

[Tpeti]

I know this thread is solved, but just let me to tell you where the engine "needs" a cooling system without thermostat. Motorbike on the race circuit. Normally they take it out because they use it such a high RPM the engine needs constant cooling. I think that is the only way where it makes sense

[Miswick]

Ha ha Tpeti, So engines can stay cooler without a thermostat? Now you've just thrown a spanner in the works

And I was just beginning to 'warm' to the idea that absence could have the opposite effect. Yeah, I know we're talking special circumstances here.

I don't think that issue will ever be solved. The whole 'cooling' thing is being 'hotly' debated out there on the net ... I never realised how much, till I was forced to learn what a thermostat did. Then you get the mechanics on the ground telling you to "stop reading the internet". Hmph!

I'm moving on to sensors next. I'm so done with thermostats.

The mystery overheating is solved ok, thankfully, though with more money spent and time wasted than necessary. 
I should really have separated out the two issues ... but then, I'm just an 'L' driver on forums. I'll be applying for my full license after a few more lessons

[Tpeti]

Ha ha Tpeti, So engines can stay cooler without a thermostat? Now you've just thrown a spanner in the works

And I was just beginning to 'warm' to the idea that absence could have the opposite effect. Yeah, I know we're talking special circumstances here.

I don't think that issue will ever be solved. The whole 'cooling' thing is being 'hotly' debated out there on the net ... I never realised how much, till I was forced to learn what a thermostat did. Then you get the mechanics on the ground telling you to "stop reading the internet". Hmph!

I'm moving on to sensors next. I'm so done with thermostats.

The mystery overheating is solved ok, thankfully, though with more money spent and time wasted than necessary. 
I should really have separated out the two issues ... but then, I'm just an 'L' driver on forums. I'll be applying for my full license after a few more lessons

I had the same issue like your one: temperature needle went up to red, on a daily basis. I have changed my thermostat and temperature sensor and water pump (because I was there already) along with my head gasket(needed anyway) and it cured. I flushed the cooling system put new coolant in and thats it.
I know for fact without thermostat in motorbikes the coolant just circulates all the time ergo it keeps at a certain temperature( cools down ) the engine but then, you just use it for half an hour. I have got a friend, he is on the track every monday and hes got a purposely built bike

[Miswick]

Jeepers Tpeti! You did a lot. It must have cost you heaps. I think I'd have given up ... I hope it stays trouble-free for you now, for the rest of its life.

I got a sensor error too. I put in a new one, but it didn't solve the problem. It was only yesterday I discovered that there are 2 sensors involved in the cooling, one visible on top of the thermostat and another one underneath it. That was the faulty one. My original mechanic didn't seem to know this at all.

I think half a minute on one of those bikes would be even too much for me ... half an hour would be a lifetime :)