Hot or Cold

CharlesY said:

It's a fact of hydrodynamics.
It seems all to do with friction on the surfaces of the pipe and in a short sharp hole such as we have, the way turbulences affect flow.

In a bigger hole there is less "edges" in proportion to area of hole - that's a fact. So one BIG hole of 100 sq mm will pass heaps more water than 100 small holes each of 1 sq mm at the same pressure.

I am told that friction in water pipes is a BIG problem, and the solution is to use bigger pipes, as these have a lower surface area of pipe for any given cross-sectional area. hence a lot less friction.

Flow through holes in plates is very complex. In fact, as I believe it is easier to "suck it and see" by experiment than to try to work it out.


CharlesY

Click to expand...

Interesting!....

CharlesY said:

I am surprised that you say 6 x 4mm holes causes over-cooling in an engine like that.

I am not doubting it - I have no evidence to do so - but I remain surprised.

So next time maybe three or four would be plenty?

Doesn't the stat have two valves, upper and lower?

If so, during the time the stat is CLOSED, the stat's lower valve plate should be wide open allowing the pump to shove the coolant down the by-pass which is a lower resistance parallel shorter route than through 6 wee holes in the stat's rim and the radiator. Hence I am surprised it has that much effect.

CharlesY

Click to expand...

There is only a single valve in the waxstat that I know of, it opens at 88oC,

When I was repairing the hgf last year I flushed the radiator with dishwasher powder and water just off the boil. We are talking aroung 94-96oC.

The rad was removed and propped against a wall on its side. I poured the hot water through the inlet, it was hand hot when it came out of the outlet 65-70oC. This was just a rad without air flowing over it - superb cooling efficiency.

As I said before the stat bulb was supposed to be balanced, not sure if that refers to the flow of the heater bypass (at 90 degrees) coming over the stat, or the position of the stat relative to the bypass outlet, eg if the 88oC stat was moved further upstream from the bypass outlet would this allow it to open sooner.

I dont know why they (Rover design) didnt have the return at around 45 -60 degrees for a better flow dynamic. This would increase flow rate at that point and therefore project the cooler water further into the block, regardless of pump speed.

This copying of the stat bulb could have purely been down to a cost saving issue (price of new tooling for new injection mould) The stat bulb is universally the same from the 1.4 right through to the 1.8 engines.

Additionally, I believe the two supports surrounding the stat core are shaped so as to provide a vortex/swirling effect. I was going to drill a single hole within the channels of each of these two supports. This will possibly facilitate cold water from the rad around the stat ring rather than through the stat.

I have seen similar flow designs in other systems,

pool filtration units, just before the impellor housing etc.

Again as mentioned there are theories on cavitation from the pump.

Like you say its complex and thats why I'm only changing one variable at a time.

Like you say its complex and thats why I'm only changing one variable at a time.
unquote


In my opinion you are looking WAY too far, and attributing WAY too much good design into this business. Water has such a huge specific heat capacity that good design is seldom needed, and that's why the Hippo system failed, because they blew it BIG TIME - they just arranged a few pieces in a cheap and cheerful manner and built lots of them without proper testing. The rest is history.

Remember why they build cars:
to make a profit. There is NO other reason.

Therefore they do EVERYTHING as cheap and simple as possible, consistent with making most profits.

Oh yes, I would like to see you holding your hand under flowing water at 65 to 70 degrees celsius. You'll need to get someone else to drive you to the burns unit because after not too many seconds at 65 to 70 degrees that's where you'll be wanting to be going, and you won't be driving!

You might hold your hand in hot air at 65 to 70 degrees for a while because of the very low specific heat capacity of air, but with water having almost 2,000 times as much SHC as air, you'll feel that heat instantly, and get cooked.

Much over 50 degrees C is getting Goddam hot for human skin including paws.

CharlesY

LR1796:
do you have the link to the thread at MG forum where they doing similar mod (bypassing) ?

CharlesY:
with KV6 where it is impossible drilling holes on the thermostat, what is your suggestion? what do you think about this mod ?http://www.landyzone.co.uk/lz/f9/dreaded-head-gasket-issue-newbie-39768-7.html

dearot said:

LR1796:
do you have the link to the thread at MG forum where they doing similar mod (bypassing) ?

Click to expand...

Here is a link to MGRover.org, these guys have fitted either the PRT or the remote stat. These are manufactured items, QED motorsport do another even pricier version.

http://forums.mg-rover.org/showthread.php?t=203775&page=3

Other links:

Porsche 944 and Megane bypass, they have lowered the temperature differential between the inlet and outlet by several degrees oC
MGF Head Gasket Failure


The PRTtemp differential across the head link,
http://web.tiscali.it/elise_s1/index.htm

More cooling system mods,
Cooling system modifications

CharlesY:
with KV6 where it is impossible drilling holes on the thermostat, what is your suggestion? what do you think about this mod ?The Dreaded Head Gasket Issue Newbie

Be it as it may that drilling a few holes in the stat is impossible. It only needs care and a long drill-bit extension. Not hard.

The idea is to make SOME hot water by-pass the stat and go through the radiator. What other options are there? I haven't worked on these Hippos.

CharlesY

Thought I would compile all of the relevant info in one place

Dearot - have you seen this there are 3 types of PRT

Link to another forum, see post 17 by Jon Baker

Smokey McPot (HGF) - MG-Rover.org Forums

"Quote

"PRT Colours
- Cream is 88° With hard Spring [Designed for Deisel and V8 applications]
- Black is 82° With Hard Spring (Designed for a V8 and used as a stopgap with K4 engines)
- Grey is 82° With Light Spring"


It means that the info shown about coolant running temperature in link below is only applicable to the cream PRT (88oC),

'+'

It would be interesting to see what effect the other versions of the PRT would have on running temp.

LR1796 said:

Thought I would compile all of the relevant info in one place

Dearot - have you seen this there are 3 types of PRT

Link to another forum, see post 17 by Jon Baker

Smokey McPot (HGF) - MG-Rover.org Forums

"Quote

"PRT Colours
- Cream is 88° With hard Spring [Designed for Deisel and V8 applications]
- Black is 82° With Hard Spring (Designed for a V8 and used as a stopgap with K4 engines)
- Grey is 82° With Light Spring"


It means that the info shown about coolant running temperature in link below is only applicable to the cream PRT (88oC),

'+'

It would be interesting to see what effect the other versions of the PRT would have on running temp.

Click to expand...

I heard this before in this forum but when I asked the detail he didnt response back.

How am I going to use this on my KV6 but?

So in your case in you use 82 degree one you dont need to make holes then...but again small flow through the hole from radiator is much better I reckon.

dearot said:

I heard this before in this forum but when I asked the detail he didnt response back.

How am I going to use this on my KV6 but?

So in your case in you use 82 degree one you dont need to make holes then...but again small flow through the hole from radiator is much better I reckon.

Click to expand...

Did you send him a PM with read receipt so you know he actually read it?

Cross referenced with MHM pics from KV6 stat thread.... 82oC is the same temp as the KV6 stat.

LR1796 said:

Did you send him a PM with read receipt so you know he actually read it?

Cross referenced with MHM pics from KV6 stat thread.... 82oC is the same temp as the KV6 stat.

Click to expand...

have you looked at MHM termostat video? its a totally different mechanism than other thermostat. I dont understand really how it works and why it design like that.

CharlesY said:

CharlesY:
with KV6 where it is impossible drilling holes on the thermostat, what is your suggestion? what do you think about this mod ?The Dreaded Head Gasket Issue Newbie

Be it as it may that drilling a few holes in the stat is impossible. It only needs care and a long drill-bit extension. Not hard.

The idea is to make SOME hot water by-pass the stat and go through the radiator. What other options are there? I haven't worked on these Hippos.

CharlesY

Click to expand...

couple of points Charlesy....
1) the thermostat on the KV6 (I can only talk authoritatively on this) is sealed within a housing that needs to be sawn in half to get at (although I now believe it might be possible to solvent weld it together again) and the main thermostat section cannot be seen. The only decent access is from the underneath and this is blanked off with a spring loaded valve. It might be a good idea to drill some bypass holes in this valve but, as mentioned, it is only held closed by a spring - holding it securely to drill it would be a significant issue. please refer to my pics and video on another thread.

2) the thermostat is on the Return from the radiator - not on the path to it! As has been mentioned previously - a crap idea

I hear you, and accept all you say.

People have been making cars with water-cooling for over 100 years, and worked out at the beginning where to fit a thermostat. So some cretin working for LandRover (or whoever owns LandRover these days) decides he knows better. I bet he doesn't drive one though ...

Perhaps a total re-arrangement of the cooling system is an idea someone will come up with?

CharlesY

dearot said:

have you looked at MHM termostat video? its a totally different mechanism than other thermostat. I dont understand really how it works and why it design like that.

Click to expand...

Can get the link up but screen is just black, a still pic but no mpeg

it works on all our pc's here - maybe its a slow load problem - it shd work ok LR

yes its only a matter of donwload speed of your internet connection...just go to the link and maybe you can see it the next day...