SVX Engine cooling "Again & Again" - Page 60

SilverSpear · #**886** 01-22-2010, 03:00 PM

Quote:

Originally Posted by SVXRide

Tony,

I call dibs on the second 'stat cover that comes off of your production line

I take it you'll machine them for a standard o-ring in place of the 'stat/o-ring combo that the stock cover supports?

Cheers,
Bill

You are soooo slow Bill

TomsSVX · #**887** 01-22-2010, 04:22 PM

Trevor, air bound means that the pump is cavitating and creating an air pocket in which there is no fluid flow.

Tony, the stat cover is easy enough to make... I would just like to get my head around how this is the fix rather than accepting it at face value... The last thing I or Dan needs is for him to take this car out on the track and have an overheating issue.

Tom

Trevor · #**888** 01-22-2010, 05:59 PM

Quote:

Originally Posted by TomsSVX

Trevor, air bound means that the pump is cavitating and creating an air pocket in which there is no fluid flow.

Tom

Tom, I know what you meant to describe, but please advise how air can be created, or how air can enter the pressurised system.

Trevor · #**889** 01-22-2010, 06:04 PM

Quote:

Originally Posted by Dessertrunner

Trevour if you don't beleive that the centrifical pump can loss prime due to a restricted suction then you must beleive in the tooth fairy so i can't help you.
Tony

Tony, you continue to misunderstand the written word. Further discussion is futile, even with the tooth on hand.

Trevor · #**890** 01-22-2010, 06:12 PM

In all of this, there is a possibility which has been ignored, i.e. to fit a pressure cap with an increased pressure rating, so as to provide extra head room in respect of temperature.

No doubt this suggestion will again be buried among superfluous stuff.

shotgunslade · #**891** 01-22-2010, 06:56 PM

Jack Laverty fitted a high pressure radiator cap, and though it helped, it didn't solve the problem. He still had problems with a puking overflow tank. He also has an electric pump and that also didn't completely cure the problem.

The "air" everyone is talking about is probably not air, but, rather vapor. There is a lot of precedent of centrifugal pumps cavitating, forming bubbles of vapor at the inlet which subsequently collapse as the fluid flows toward the pump outlet.

To get coolant belching out of the expansion tank, there is definitely boiling happening. The question is whether that boiling happens because there is uneven distribution of coolant in the bock, or because, as Tony suggested, the pump gets vapor bound, temporarily interrupting coolant flow completely, resulting in lots of boiling inside the block.

I have a feeling that both issues play a part in our problem.

Trevor · #**892** 01-22-2010, 07:19 PM

Quote:

Originally Posted by shotgunslade

Jack Laverty fitted a high pressure radiator cap, and though it helped, it didn't solve the problem. He still had problems with a puking overflow tank. He also has an electric pump and that also didn't completely cure the problem.

One experiment should not out rule out further investigation.

Raising the pressure must provide head room for an increase in temperature. Whether or not this will be sufficient to cure a problem, will depend on the extent of each individual problem.

Dessertrunner · #**893** 01-22-2010, 07:47 PM

Trevor I changed the cap to a higher pressure as did other and no advantage was found. In addiation I and one other ended up blowing the heater core because it can't stand the higher pressure.

Dan
You are 100% right it is not air getting into the system as everyone thinks. I can induce the same problem on my irrigation pumps and there is no air getting in.

Guys put a proper temp guage into the top pipe and run a couple of tests like I did and you will find as the revs go up the system will fail and you will have to cut revs. Then change the cover and see what result you get.
Have a great day.
Tony

SVXRide · #**894** 01-22-2010, 09:22 PM

Tony,

About those custom water pump inlets...

-Bill

Dessertrunner · #**895** 01-22-2010, 10:25 PM

Bill I won't be milling the final as I think the easiest is to weld a 90 degree bend onto a flange. Need to find the right water pipe to make it all match as current the flange thermo cover faules up the thermostate.
Sounds like you guys are keeen to go forward. How many guys are going to change the bottom pipe in the radiator?
Tony

SVXRide · #**896** 01-22-2010, 10:46 PM

Quote:

Originally Posted by Dessertrunner

Bill I won't be milling the final as I think the easiest is to weld a 90 degree bend onto a flange. Need to find the right water pipe to make it all match as current the flange thermo cover faules up the thermostate.
Sounds like you guys are keeen to go forward. How many guys are going to change the bottom pipe in the radiator?
Tony

Tony,
I think my initial inclination is to try what Dan suggested and keep the bottom outlet of the rad on the PWR as is and splice an adapter in line to go up to the 45mm ID of the modified water pump inlet. If this doesn't work, then the next step would be to modify the outlet on the rad.
Cheers.
-Bill
p.s. make sure to post up the "right water pipe" so those of us state-side can source it and give the welding a go.

Dessertrunner · #**897** 01-23-2010, 12:40 PM

Given the passage of time and the number of posts I want to go over the details of one of my trial that I beleive pointed fair and squarely at the thermos cover being the problem. I think it is important to discuss this info through so everyone is on the same page. Feel free to ask question as I want everyone involve here to understand what was found. The purpose of this is to get everyone on the same page as me.

As you will remember I build the mule with an engine, radiator, clear pipes and the water pump drive by an electric motor. Due to the size of the motor the max engine rpm equilivant I could get was around 5,ooo rpm.

- First test air started to come out the overflow of the radiator and both top and bottom pipes filled with air bubbles at any speed above 2,000 rpm. As you will remember there was grest debate about putting an over pressure to stop this. I did not agree that it would fix the problem but did give it ago and there was no improvement. By the way the unit had pressure guages on the different parts of the engine including the pump inlet which was showing a vacum of -5 psi. At this time there were a number possiable causes put foward but no way to say clearly that this is the cause due to the fact that the mule had to many variable.

NEXT STEP
I decide at this point that the system had to be tests with the water pump only so I mounted it on its own driven by an electric motor. On the inlet and outlet of this pump I mounted a standard Subaru Thermo cover. The outlet of the pump was taken into a Tee and one leg of the Tee went back to the inlet of the pump. The other leg of the Tee went up vertical to enable addiation of water to the system.
1st test - the pipe and Tee were 32mm ID so I turn the motor on and while the air didn't happen till around 2-3,000 rpm it still happen and there was nothing I could do to stop it. I gave up and left the system for a couple of days till I condensed the results. I have attached a photo of the air in the pipe.

2nd test - I decided to try with a bigger pipe so I purchased the respective bits at 43mm ID. I change the suction on the pump to 42mm ID and left the outlet at the same size that was in the previous trial. What I found was that once the air had cleared from the block you could run the pump flat out a 5K and it was very hard to see the water movement, the problem had gone away.

Its time to open this up to discussion and questions as I don't want to go to far with out getting everyone clear as to the events. I will make one statement and I can support it if nessacery. "The air in the system is not air that leaked in it is vapour realeased simlar to boiling as was mentioned earlier I think by Dan" happy to debate that with anyone who wants to challange me but they need to product documentry evidence to support there postition not pluck there ideas from blue sky.

So go for it I need to go away for about 1 hour to work but I will check back on my return. Due to bad connect the photos are in the next post.
Tony

Dessertrunner · #**898** 01-23-2010, 12:45 PM

Here are the 2 photos, the first is smaller pipe with air the second is larger pipe no air.
Tony

Trevor · #**899** 01-23-2010, 04:02 PM

Tony,

I am sorry that argument will upset you, but there are facts which must be recorded.

Without plucking ideas from the sky, I again point out the fact that your test mule, was/is not properly pressurised.

The described experiments, therefore in no way represent an operating, closed circuit, pressurised cooling system. You have stipulated that documentary evidence should be presented. This exists in detail, within earlier posts.

Sincerely, Trevor.

Dessertrunner · #**900** 01-23-2010, 04:58 PM

Wow Trevor you are right on cue, I DID PRESSURISE the system at one point and it made no difference.
You have not come up with one crediable reason why the system needs to be pressurised just that it seems like a "bloody good idea". Happy for you to provide a sicentific paper or simlar to back up your statements.
If it is to prevent air getting into the system its not needed.

Happy to debate the issue till the crows come home.
Tony