Interesting V8 block tester

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Originally Posted by p38arover

I'm not sure that running pressures much higher than, say, 40psi would be a good idea.

We aren't looking at the engine pressurising the coolant but for leaks the other way, from the water to the cylinder.

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Ron, when you think about it the water pressure in the block shouldn't be any higher than the pressure relief valve in the radiator/header tank. I would imagine running 170 psi through the water jacket could destroy the liners, I have seen bores crushed from the water jacket side with water that had frozen. Consider that the radiator cap releases pressure at around 15psi (or whatever your cap is set at) I can't see the value in pressurising the water jacket to extremes (even 40psi), I would be very careful, Regards Frank.

I agree, Frank. I think Andy's suggestion of 170psi is too high.

Yes Ron, the block's water jacket is not designed for such high pressures, I think if 170psi was pumped into the water jacket I think it would cause more problems than you could poke a stick at, Regards Frank.

Exactly the same issue was raised on the RangeRovers.net forum. It was thought that one could ruin a block in that way.

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Originally Posted by 350RRC

Mine is ok @ 42 - 44. @50 it would probably need a bigger radiator.

I actually have the opposite prob at the moment. One fan runs with ign on, the other is wired through an adjustable thermo switch.

In ambient temps of 2 deg or lower it won't get up to temp (just over 1/4 on the gauge, oil temp about 60) so the heater is not warm enough for comfort. :(

I'll soon be fitting either a simple disconnect switch or another thermo switch for the first fan, as I don't want both fans to switch on at the same time.

The whole set-up only cost about $250 new inc the shroud.

cheers, DL

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Get a dual temp switch. Echlin/NAPA, what ever you want to call them these days, or Tridon do a large range of fan switches with different on/off temps

see these links here.

http://img96.imageshack.us/img96/1926/tridon17gb.jpg

http://img96.imageshack.us/img96/2451/tridon22kf.jpg

http://img442.imageshack.us/img442/4646/tridon38ba.jpg

http://img96.imageshack.us/img96/1051/tridon40em.jpg

http://img442.imageshack.us/img442/3672/tridon52bu.jpg

http://img96.imageshack.us/img96/62/tridon61yo.jpg

Worthwhile saving these for reference.

Using a thermo housing for a 3.9 with A/C will give you somewhere to mount it. Not sure on the three fitty tho, but you could just drill one in.

I have a TFS100 and TFS102 (first link pic), but the 102 is too high, 100 stays on too long and drops it too much so the TFS109 is what I am looking for to keep a happy medium.

The dual temp switches you want are on the last 2 links.

Cheers Andrew

I am curious how the block can be damaged by putting 170psi through the water jacket? It gets 170psi through the other way from the compression against the top of the liners, so why will the other way around damage it? Or will it blow out a welsh plug or somthing?

Andy

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Originally Posted by andrew e

I am curious how the block can be damaged by putting 170psi through the water jacket? It gets 170psi through the other way from the compression against the top of the liners, so why will the other way around damage it? Or will it blow out a welsh plug or somthing?

Andy

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If you have a leak and pressure gets between the casting and the liner, it can deform the liner from the differential pressure ( ie no pressure inside the cylinder & 140psi on the other side) and cause it to separate further from the cast or even shatter the liner. Liners are cast iron and do not hold up well to being put under high pressure, especially something as thin as these are.

I dont know of anyone that tests above 40psi, and I worked for two Diesel Engineering outfits and have been a supplier to reconditioners and engine builders for a long time.
40 psi is 3+ times the operating pressure of a system anyway.

The only time you use a higher pressure is for head testing.

Some may say that the cylinders are subject to high pressures on the inside when engine is running, this is true, but only in a very small swept area of the cylinder for an minute amount of time and this pressure is subjected to the strongest and most supported area of the liner, not forgetting the block holds it all together anyway.

Cheers

Andrew

Thanks Andrew.

The Tridon info is here on Outers:

Outer Limits 4x4 Board :: View topic - Thermo fan info

I like the adjustable switch I have on one fan so I'll be installing another. Makes it really easy to get right without stuffing around.

Back on topic........... I can recall PLR (from down the Prom way) on this forum posting somewhere the different colour codes for the smidge of paint on bare 4.6's that denoted some quality aspect of the block.

cheers, DL

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Originally Posted by 350RRC

Back on topic........... I can recall PLR (from down the Prom way) on this forum posting somewhere the different colour codes for the smidge of paint on bare 4.6's that denoted some quality aspect of the block.

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Yes, the wall thickness and therefore which blocks were to be used on 4.6 engines. Unfortunately the paint is in the valley so after some years of running, it's no longer distinguishable.