SVX Engine cooling "Again & Again" - Page 25

oab_au · #**361** 10-25-2009, 11:12 PM

Looks to me that where Tony has taken the outlet pressure gauge, is on the block, not at a gallery. Can anybody tell if that is in the left side jacket, or in the pump outlet gallery that he is talking about?

Harvey.

Dessertrunner · #**362** 10-26-2009, 12:40 AM

Harvey/ Matt here are the images behind the water pump. Were my finger is is were the pressure is being taken from. Coolent porting goes left for the right head and straight up for the right head.
Tony

Dessertrunner · #**363** 10-26-2009, 03:14 AM

Here is a new test guages were hard to read as they moved a lot also the 6.5k was at Zero then built up. Thermostate is still in.
Tony

SilverSpear · #**364** 10-26-2009, 03:45 AM

Nice Tony! Did the guy told you he resolved this issue permanently? As there is no overheating of one side more than the other?

Well I glimsed onto that point before but it was for the upper outlets rather than the lower ones. but I would still think that we need a Y pipe similar as what YT did.

What do you think?

Dessertrunner · #**365** 10-26-2009, 03:46 AM

Just figured the guages were jumping around because I forgot to top up the cooling system so it had a bit of air.
Tony

Trevor · #**366** 10-26-2009, 04:57 AM

Quote:

Originally Posted by Dessertrunner

Here is a new test guages were hard to read as they moved a lot also the 6.5k was at Zero then built up. Thermostate is still in.
Tony

I gather that the gauge was following rapid fluctuations in the pressure being monitored. This can be overcome by inserting a damper restriction within the gauge connection.

Fit a small pierced disc, or braze up the nipple and drill a very small through hole, so as to restrict the speed of the flow. You probably have a jet drill which will do the job.

At which point in the circuit was the fluctuation worst? I would expect this to be the pump inlet. You have hit on a way to register points of turbulence.

You point out "also the 6.5k was at Zero then built up." I would expect this comment to refer to the pump inlet, but confirmation would be appreciated. If you can dampen the gauge response, you will be better able to record the exact situation in respect of mean pressure.

The graph now posted, is quite different from that which you posted earlier and about which I expressed doubts concerning validity. In point of fact I completely discounted it as evidence. This new graph is more in line with expectations.

Please also advise whether the thermostat was open when the new readings were taken. I know that recorded temperature provides you with an easy means.

A closed thermostat, opening during slowly increased engine speed, could induce the dip in pressure shown through 3,500 RPM, with the restriction of the bypass circuits accounting for the high pressure at start up. Otherwise this is aspect is difficult to fathom.

Good stuff, this. Trevor. N.B. Not --- Good, stuff this.

Dessertrunner · #**367** 10-26-2009, 05:09 AM

Trevor,
The thermostate was open on all tests. The reason the guages moved around was the air in the coolent system. Don't get to happy that the 6.5k didn't go to zero as the air temp was a lot cooler today during the test. Also getting a bit concerned at have a engine screaming at 6.5k no load, not good for my drive car.
Tony

Trevor · #**368** 10-26-2009, 06:26 AM

Quote:

Originally Posted by Dessertrunner

Trevor,
The thermostate was open on all tests. The reason the guages moved around was the air in the coolent system. Don't get to happy that the 6.5k didn't go to zero as the air temp was a lot cooler today during the test. Also getting a bit concerned at have a engine screaming at 6.5k no load, not good for my drive car.
Tony

Thanks Tony,

Air in the system during the test means that the figures are somewhat in doubt and another is called for. More work for the willing.

The top manifold pressure is a key indicator and shows that there is unlikely to be any untoward restriction upsetting the overall flow. It is important to establish just how far this pressure rises at the intended maximum RPM. However, I am right with you in your concerns regarding high RPM without any load.

Not sure what you are saying here. "Don't get to happy that the 6.5k didn't go to zero as the air temp was a lot cooler today during the test." Please advise.

It would be worthwhile to run a line to the inside of the car, so that you can monitor this vital pressure while under way. There could be a clue or two yet to be discovered. However, a hot shower must be avoided.

Dessertrunner · #**369** 10-26-2009, 01:04 PM

Trevor the test was done for only one reason and that was to see if the majority of the back pressure was in the engine block or after that point. It servied that purpose quit well so I won't be doing it again.
The next test will be as Harvey suggested "with the thermostate removed" and at simlar air temps to the first time I did it.
A follow point about the work on the block the guy did it with a die grinder with the engine still in the car, sound fimilar, isn't that what Rally Bob and Tomtalked about?
The weather has gone cold so can't do the next test till it gets warm again.
Tony

dynomatt · #**370** 10-26-2009, 04:10 PM

I think I might have to pull my pump off and have a look...I can't quite work out what is machined and where the twin turbo guy saw the restriction.

Dessertrunner · #**371** 10-26-2009, 08:33 PM

Matt its impossiable to show with a photo.

Dessertrunner · #**372** 10-27-2009, 08:27 PM

I may get beaten up here but I feel it is conclusive from the data I have got that the pump suction is boiling at high RPM. I am 100% certain that Harvey was right when he said the low pressure on the inlet would cause the engine to boil. It make sense and the harder you push the rev or engine heat the bigger the problem. This has been confirmed by my friend Steve buggy. Based on this I intend on tracking down the high pressure zone so we know were to approach the replumbing. I don't need to run at high reves I just need to find the areas of restrictions. Next test point will be the top of the radiator so we will have four guages in the engine. Will give this ago in the near future.

I have suggested to Steve that he taps in to the front plug on the out let of the pump and put in a line returning to the two pipes on the inlet side. We both understand that this could cause the enigne to over heat at slow speed he said it would be a change. THis suggestion will mean that the suction will always be pressure feed so there should be no way it can lose prime and boil. What I am proposing is not a stupid as it sounds they use this method to stop deep well bore pumps losing prime. Its worth a try.
Tony

oab_au · #**373** 10-27-2009, 10:43 PM

I agree Tony that will tell us if it is the inlet boiling, causing the pump to cavitate and stop pumping. It will allow the pressure in the inlet side to increase to above the boiling point of the water in there.

Then we can fix the cause of the low inlet pressure.

Harvey.

svxistentialist · #**374** 10-28-2009, 02:33 AM

Quote:

Originally Posted by Dessertrunner

I may get beaten up here but I feel it is conclusive from the data I have got that the pump suction is boiling at high RPM. I am 100% certain that Harvey was right when he said the low pressure on the inlet would cause the engine to boil. It make sense and the harder you push the rev or engine heat the bigger the problem. This has been confirmed by my friend Steve buggy. Based on this I intend on tracking down the high pressure zone so we know were to approach the replumbing. I don't need to run at high reves I just need to find the areas of restrictions. Next test point will be the top of the radiator so we will have four guages in the engine. Will give this ago in the near future.

I have suggested to Steve that he taps in to the front plug on the out let of the pump and put in a line returning to the two pipes on the inlet side. We both understand that this could cause the enigne to over heat at slow speed he said it would be a change. THis suggestion will mean that the suction will always be pressure feed so there should be no way it can lose prime and boil. What I am proposing is not a stupid as it sounds they use this method to stop deep well bore pumps losing prime. Its worth a try.
Tony

That's an interesting suggestion Tony and it could well work. I wish you the best of luck, that's worth a shot.

At to finding the restriction or restrictions, I underlined above your phrase "Areas of Restrictions" above. Plural.

Best case scenario here would be to measure low pressure behind the pump and see where the high pressure starts. If it happened to be one major passage such as the transfer pipe and it could be relieved to let flow resume, that would be a neat and easy fix.

As mentioned earlier and by you above if the flow restrictions are plural and inside the block it could mean disassembling the engine and enlarging some coolant passages to really cure the bug.

Reducing the pump rotor's high speed pumping ability and using the feedback pipe to keep it primed and thus limit boiling may well just do the business.

Keep on plugging it man.

Joe

Dessertrunner · #**375** 10-28-2009, 02:14 PM

Harvey you owe me a diagram.