20v cooling issues

[JustenGT8]

Relocated sensor and all appears well I feel better thrashing it now I can see what's going on...mind you, now oil pressure seems low I suspect dodgy autotechnica gauge

[Sam_Q]

Heater lines should never be looped, always blocked or else it's just a radiator bypass and an effective one at that.

[dnegative]

+1
Block off the heater lines, 5/8 heater hose looped flows quite a bit of coolant

[DX20VT]

Heater lines should never be looped, always blocked or else it's just a radiator bypass and an effective one at that.

Yeah with no resistance of the heater core in the loop that is quite a lot of water that bypasses the radiator and does not get cooled.
Try blocking them and it will help with cooling.

[JustenGT8]

Hmm, will be tricky as the 'loop' is actually braised copper pipe....I might be able to crimp it down a bit to act as more of a restriction?

[allencr]

What HG?
For that setup, it needs the one that'll exit at 4 ex after flowing by everything else, does it?

[JustenGT8]

What HG?
For that setup, it needs the one that'll exit at 4 ex after flowing by everything else, does it?

Huh? Headgasket? It's a stock engine with 11vnty kms on it...been running in the current configuration since 2007

[trdee]

Pressure can be as low as 10-15psi at idle on a stock motor. Should go up to about 70ish and then the bypass should regulate it from there.

Heater lines may not be an issue. Just keep an eye on the temp now that the sensor is in the right place

[JustenGT8]

I think the oil pressure sender must be a bit off.....pressure reads around 50psi cold at idle. 30-40 hot driving...up to 50 maybe at revs...but reads 0 at hot idle...yes 0 LOL. clearly not the case or it wouldn't still be alive. oil system is stock bar a non genuine oil filter.

i did briefly attempt to run the stock pressure sender wiring off it as well for the dash light...dash light worked but not the gauge as the voltage signal was obviously effected....i can't see this having munted the pressure sender though?

[Sam_Q]

What HG?
For that setup, it needs the one that'll exit at 4 ex after flowing by everything else, does it?

yes that's right, which would mean an original gasket.

[trdee]

I think the oil pressure sender must be a bit off.....pressure reads around 50psi cold at idle. 30-40 hot driving...up to 50 maybe at revs...but reads 0 at hot idle...yes 0 LOL. clearly not the case or it wouldn't still be alive. oil system is stock bar a non genuine oil filter.

i did briefly attempt to run the stock pressure sender wiring off it as well for the dash light...dash light worked but not the gauge as the voltage signal was obviously effected....i can't see this having munted the pressure sender though?

perhaps oldmate fitted the sensor with non sensor safe thread sealant and it's giving spurious readings? or maybe its just an el cheapo speco/supercheap/etc gauge lol.

50psi cold idle sounds right, i was getting similar numbers on my setup. obviously the hot idle is not right though lol. what ecu is the engine running? if aftermarket, perhaps it would be wise to invest in a race dash like a stack/racepak/race technology etc. if not, a set of defi or speedhut gauges may be the go.

[trdee]

Whilst we're on this topic - SamQ you know more about 20vs than me. I have read previously that the blacktop rear water housing is different to the silvertop, and that they use a bigger thermostat out of an SW20 or whatever. Is this true? When doing a part number cross-check on toyodiy, the part number comes up for cars fitted with the silvertop as well... but when i click on the link the part number for the silvertop item is then a different number. Is this because they are different, but will still both bolt up to either engine or something weird like that?

Or to put it another way - If I have a blacktop head with no rear water housing, can I bolt a silvertop water housing and thermostat etc onto the blacktop?

[DX20VT]

Or to put it another way - If I have a blacktop head with no rear water housing, can I bolt a silvertop water housing and thermostat etc onto the blacktop?

The blacktop and silvertop do interchange, but they are different.

The thermostat sizes are different, and the covers are too,
so the thermostat over must match the housing.

Also no TRD thermostat listed for the silvertop, only the blacktop.

[lexsmaz]

Hey Justen, you should be able to get a copper welsh plug to tightly fit inside the copper pipe you have & drill a small bleeder hole in it to act as a restrictor & either push it into the pipe or braise it into your existing copper pipe, I did a similar thing with my 2jzgte the reason I didn't block it off totally is so it allowed the pipe to bleed any air out of it instead of creating a air lock, i also off set the hole to the top so it can bleed air properly ..

Your choice as to what you end up doing ..

Regards ..

Rob ..

[JustenGT8]

Cheers rob, worth considering. Seeing I could do with some more room in that area of the 'bay' I'll have a serious look at SamQs billet bypass setup as a long term solution.