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Preparation for summer traffic


iana

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Bolts    just be carefull 

Testing a stat is not conclusive without some care , boil it like an egg is a waste of time 

Needs a slow temp,rise and circulation of  the water and noting the start of opening often obscured by steaming

I would just buy a new one .

Pete

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Pete, I can't say why they started with 71c but it's also given the the Workshop Manual. If you remember the old set-up was fit a hotter stat in the winter and a colder one in the summer. 82c was a compromise between the two stats. If it's a really hot summer it's not a bad idea to fit a cooler stat as per the original set-up.

Dave 

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49 minutes ago, Pete Lewis said:

Makes you wonder if the   tepid   71 derived from a thermosyphon of  the past   its incredibly low for a then modern ohv engine

In all my years and  many makes never seen one that low,   interesting !!!

Pete

 

I agree Pete, a 76c or 78c would have made more sense.

Dave

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Took the car for a run out today, the heater seems to be working a lot better now, so the reset of the valve seems to have got water flowing through the heater. Now just to sort the thermostat and an anti freeze refill

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The problem with prepping for summer is remembering all those jobs you didn't do last summer. And all the bits that looked shiney and new which are now corroded because you(I) forgot to give them a mist of lacquer or rub over with an oily rag before winter. 

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  • 2 weeks later...

Managed to carefully remove the thermostat housing bolts, they were tight to say the least. Anyway they’re out and I’ve cleaned them up but wondering if it’s better to replace them - are they anything special or will a general bolt be ok? 

Also what’s the implication of running a summer stat all year round? We rarely get frosts or low temperatures where we live, the car is garages and if it was a bad winter the car wouldn’t be used. 

I’m thinking the summer stat would be better in the traffic etc (or will it cause the engine to overcool?)

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Have a think about the thermostat.

It opens at a specific temp, 82 or 88 on our cars, higher on modern cars. And coolant boils at over 110 degrees.

If the stat opens at 82, rather than 88, the radiator will still cool and you have a 6 degree "advantage". Well, not really an advantage, but a bit more leeway in case the cooling system does not work as well as it should.

 

An 82 degree stat will be fine all year, the c=vast majority of owners do not sway thermostats, and I reckon most are using an 82. I wouldn't use lower, if the 82 is a problem get the cooling system sorted....

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in many parts lists and wsm  there is no summer winter , what they state is  european  climate  82c  hot climate  78c

cold climate  88c  nowhere does it mention swapping to suit  the  English  weather .

its a fit and forget item , swap for new if its boiled at any time or you wish to change it as a service item  especially as most over heating myths on here end up as electrical problems with gauges and senders 

Pete

 

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Thanks both, I’m happier now the heater is working (the car was toasty warm on the run yeaterday), the water seems to be flowing properly round the system, so it’s now just a case of renewing the thermostat and replacing the antifreeze so I know what’s in the system.

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Worth doing a simple engine flush while draining (or have you already been through that? I can't remember)

The important bit is the block drain plug, below the manifolds near the rear of the engine. Take it out, often needs a poke. Then with the rad hoses disconnected, push a garden hose hard against it, full on. That will move most rubbish in the block... then heater both ways a few times.

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19 hours ago, iana said:

Also what’s the implication of running a summer stat all year round?

A cooler thermostat means your cabin heater will be that bit cooler. If it weren't for the hassle of procuring a new gasket and scraping the surfaces clean, I would put a hotter thermostat in mine for the winter months.

Cheers, Richard

<THINKS> I wonder if a thin sheet of Viton would make a good re-useable gasket???

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and to add.............cooler means richer mixtures are required 

82c is the std to have for all year running ,  88c was introduced more in the late 70s as emmisions took hold  , hotter means leaner mixtures could be achieved  so a late 1500 may spec a 88c stat   all tied in with  SU waxstat jets and strombergs CDSEV  etc for emmision reductions 

who remembers things like Avengers with white coked tail pipes of the day 

Pete

 

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I've always wondered how, if your engine is running hot, putting a lower temp thermostat is supposed to make it run cooler! Assuming the original is good to me the only difference seems to be it will open sooner on start up and start cooling earlier....

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1 hour ago, Pete Lewis said:

  88c was introduced more in the late 70s as emmisions took hold  , hotter means leaner mixtures could be achieved

It's a little more complex than just "leaner mixtures". If the engine is hotter, the thermodynamic behaviour allows a bit more "heat" (read: energy) to be made useful, so hotter combustion gives higher efficiency regardless of mixture. Meanwhile, lean mixtures have a lower thermal inertia so you get hotter running because you're leaner. But if you have to retard the ignition to tolerate the leaner mixture, then (some of) that extra energy is thrown down the exhaust instead of being used. Burning hotter also (usually) means burning more completely, so reducing your HC emissions (and CO but not CO2). However, really hot (like diesel or very lean burn) tends to increase NOx emissions.

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4 hours ago, johny said:

I've always wondered how, if your engine is running hot, putting a lower temp thermostat is supposed to make it run cooler! Assuming the original is good to me the only difference seems to be it will open sooner on start up and start cooling earlier....

Always wondered that myself. How does it make the difference. It obviously must.

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Most modern cars seem to run with the gauge at around 90’c. The exception seems to be bmw in that it runs at 100’c.  That’s in diesels. Skoda, merc and I think Audi all sit at 90 on the gauge, my bmw ran at 100. 

And was still Eu 6 spec without the use of adblue. 

Or perhaps that was due to software tricks like vw🤔

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Thermostats modulate  they dont just open they open close and modulate in between if you lookmin the header you will see the flow and ebw as it allows hot out and cool in, as soon as ot detects the cool it closes down until  it reaches opening and this carries on continuously  in general the rad cools around 20c so the in going is not too cold , or there would be a lot of heat stress developed

You domt need the block and head having violent temperate changes so the stat keeps on working all the time opening to closing 

For  All its working life

On testing stats our hot tank would raise the temp in 0.1c increments and plot the opening rate vs temperature

Youre not boiling an egg    they are quite clever bits of kit .

Pete

Pete

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Ok I can understand the modulating effect but if an 82* thermostat is working fine in the winter why shouldn't it be ok in summer? If the coolant temperature has gone too high the thermostat will be fully open and putting in a lower temp thermostat won't help! 

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I suppose that depends on what exactly an 82C stat means. If it means that it begins to open at 82C, and if the characteristics mean that it takes, say, 15C to fully open, then it's not fully open until 97C. If the engine wants to run at 90C then an 82C stat is a little over half open, which gives enough flow to provide the required cooling if the radiator is exposed to 10C air. In 25C air it would need to be a bit more open, and a 78C stat will help.

Of course, the engine may not care much whether it's at 90 or 95, and the difference between 10C and 25C is actually between 80C and 65C (difference between radiator and air) which sounds less dramatic, and the speed of air flow over it will have a much bigger effect. As Pete said, the 82C stat is an all-year-round spec. so by implication it's probably fine in the summer.

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The temp marked is the start of opening , after that its free to open more or less it has no idea about the weather and doesnt care 

The lets call it  the valve will open progressively  the longer and hotter the coolant becomes 

So in winter I may open close and float between the two every  60 seconds in summer it may float every 15 seconds 

The cycle  depends on the heat in the block and the temp of  incoming coolant , the thing just changes to suit the needs 

All year round 

Go   back to the old  idea of blanking or muffle the radiator,  it may keep cold air from the engine bay but if the coolant is cold 

The stat  stays shut the is no circulation of coolant through the radiator it just  does the short cut via the bypass which  may involves the heater matrix .  Not on a triumph.

Some stats have a back plate that closes the heater bypass if they get fully open  again not on triumph, so more flow to the rad on extreme heating .

Pete

 

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Ahh I thought I saw somewhere the thermostat was fully open about 3deg after the start temperature. 15 to 20 makes more sense although I haven't seen much of a change in running temp on my gauge by going to a 78 thermo☹️

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