GRP151

Restrictor Plug or Constrictor Clamp by GRP151

66 posts in this topic

Mechanical, Chemical, Civil (Hydraulic) Engineer. Pretty impressive...

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4 hours ago, tolsen said:

Flow area in this constricted hose is far too large and will not work at all. 

CC4.JPG

I estimate above flow area no less than 300 mm2. No way that will have any effect at all. 

 

 

When I engineered this design I found that I had results with the 3 nuts stacked in my first test vehicle. On another vehicle I reduced it to 2 nuts stacked. My conclusion was that there was an air pocket in the 2nd vehicle and I didn't want to bleed the system. Now ask yourself this question. Why is it that some of these smarts have very little heat while others that have not been modified have plenty? From my experience with over 100 vehicles the problem after replacing a thermostat in some cases was still air in the system. The difficulty is bleeding the  air out. Like one of my Fiero's. Same design as the Smart. Rad in the front engine in the rear. Try and bleed this baby without a vacuum system!

I think the majority of the problems with these cars is an air pocket develops and is difficult to remove. When you end up opening up the system to install a smaller orifice like a small rubber tube or a plastic part you end up bleeding the system. Was it the bleeding that solved the problem or the reduced orifice size. You figure it out!

 

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Posted (edited) · Report post

Bleeding air out of cooling system is easy and not the problem provided you got your head correctly screwed on. 

 

Optimum restrictor size is 8.5 to 9 mm diameter hole. This corresponds to about 1.4 mm gap in the constricted hose. Somebody ought to remove hose, fit clamp, measure gap and work out required clamp spacer thickness. 

Edited by tolsen

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13 hours ago, tolsen said:

Bleeding air out of cooling system is easy and not the problem provided you got your head correctly screwed on. 

 

Optimum restrictor size is 8.5 to 9 mm diameter hole. This corresponds to about 1.4 mm gap in the constricted hose. Somebody ought to remove hose, fit clamp, measure gap and work out required clamp spacer thickness. 

 

Sounds like constrictor will work effectively depending on the opening size. According to your thoughts maximum opening size should not be greater that 9mm round.Currently the opening size is approximately 25mm judging from the images. That is quite a drastic difference! So according to your math 1 single nut as a spacer should be sufficient. 

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I think you will need washers as well for fine tuning. 

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A restrictor or constrictor will worsen lack of heat if you have a leaking thermostat. The higher differential pressure will increase leakage rate and heat loss. 

That is why I have always advised to check thermostat and renew if it fails to seal. 

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On ‎10‎/‎16‎/‎2017 at 1:36 PM, tolsen said:

A restrictor or constrictor will worsen lack of heat if you have a leaking thermostat. The higher differential pressure will increase leakage rate and heat loss. 

That is why I have always advised to check thermostat and renew if it fails to seal. 

 

That doesn't make any sense regarding higher differential pressure. By restricting the flow from about 25mm opening  to a  9mm  opening you are creating a differential in pressure. You are contradicting yourself here Tolsen

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28 minutes ago, GRP151 said:

 

That doesn't make any sense regarding higher differential pressure. By restricting the flow from about 25mm opening  to a  9mm  opening you are creating a differential in pressure. You are contradicting yourself here Tolsen

I stand by what I said.

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Test your thermostat by blowing and sucking on the large barb that goes to top of radiator.  The small check valve will open when you blow allowing a minimal amount of air through.  Then try sucking.  Check valve should seal and you should be able to suck yourself onto the barb creating a vacuum.

 

if thermostat fails the sucking test, then the increased pressure differential made by the restrictor plug or constrictor will increase flow of warm coolant to radiator thereby worsening the heat loss.  That is why you need a fully functional thermostat to reap the benefits of the restrictor or constrictor.

 

 

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Replace the thermostat with a 451 type bleed out ALL the  air and everything will work perfectly. That is what l have concluded  from the restrictor/constrictor mods on this site.

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Which 451 thermostat? There are two types. One is same as for the 450, the other one is five times as expensive.  

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12 hours ago, tolsen said:

Which 451 thermostat? There are two types. One is same as for the 450, the other one is five times as expensive.  

 

Thermostat GATES TH40390G1 for Smart

This item fits 2 version(s) of the Smart Fortwo 2007 451 [2007-2016] Coupe 0.8 CDi:

 

 

https://www.ebay.co.uk/itm/Thermostat-GATES-TH40390G1-for-Smart/232190631852?epid=1015962934&hash=item360fa3dfac:g:DwkAAOSw2xRYZkIe

 

http://www.ebay.ca/itm/Engine-Coolant-Thermostat-Fits-SMART-Fortwo-Cabrio-City-Coupe-450-0-8L-1999/172670392773?hash=item2833f519c5:g:8z0AAOSwPcVVkQv0&vxp=mtr

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GATES TH40390G1 is one of the worst thermostats ever made.  Its disc does not seal and the body may come apart.  It is extremely poorly designed.

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6 minutes ago, GRP151 said:

Which one do you recommend?

Original Smart.

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4 hours ago, Ritchie said:

I bleed the air out by removing the temperature  sensor

 

 

Above video shows thermostat for a petrol Smart 450 or Roadster.  Note that this thermostat has a restrictor orifice in its bypass.

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The original Smart thermostat is made by GUSTAV Wahler GmnH u. Co. KG. 

Wahler part number is 3146.90D. 

Beware there lots of fake China thermostats out there. That is why I now only recommend original Smart. 

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6 hours ago, tolsen said:

The original Smart thermostat is made by GUSTAV Wahler GmnH u. Co. KG. 

Wahler part number is 3146.90D. 

Beware there lots of fake China thermostats out there. That is why I now only recommend original Smart. 

 

....and what is the reason you believe is the difference in the fake China version? You mention the Gates doesn't seal properly. Is that the blow test technique ?

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Posted (edited) · Report post

The China made Wahler pattern thermostats I’ve tested all had the check valve fitted wrong way around meaning it will be very difficult to bleed air out and they will constantly leak hot coolant to radiator. 

 

The Gates is just very badly engineered. Its closing element is simply a crudely stamped out, non deburred metal plate so cannot seal against seat. The housing is in two parts held together by too small and too weak integral dogs. These fail when under pressure leading to major loss of coolant. 

Gates should limit themselves to making rubber belts.  Products like the TH40390G1 thermostat will tarnish their reputation. 

Edited by tolsen

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I read somewhere on this site that blowing into thermostat inlet and covering one end to check leakage but I cannot remember the details. Does that make sense?

 

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2 hours ago, Ritchie said:

I read somewhere on this site that blowing into thermostat inlet and covering one end to check leakage but I cannot remember the details. Does that make sense?

 

There no need to cover any end.

 

BadThermostat.jpg

 

Above thermostat is brand new but no good as made in China.  This is the one that has the check valve fitted wrong way.  Barb where water runs out goes straight to radiator.

On a good thermostat you should be able to suck yourself onto that barb.

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I found an image of the thermostat. I assume it had to have been cut open and does not disassemble easily.

I m having some difficulty understanding your barb explanation.

What does " Barb where water runs out goes straight to radiator " mean?

 

 

MotoRad2.jpg

Disc_m_o_ring_1.jpg

Disc_m_o_ring_2.jpg

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i think he means the barb end in the picture with the water running out of it is the one that goes to the radiator

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It is always the largest hose barb that goes to radiator. 

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