Thermostat bypass line

[Riceburner]

I have seen and found a few zeds running a tstat bypass line. It comes out of the lower tstat housing loops around the front of the head and goes down into the main water return fitting on the timing cover (hope that makes sense). My understanding is it would ensure a very even warm up of the motor and head.

 

What are the pros/cons of this setup? Does anyone have this setup? Any info or pics would be helpful.

 

Sorry for the shabby pic, it's the copper pipe running past the front of the head

[Riceburner]

From what I have been able to find so far this bypass is to stop hot spots forming in the head until the stat opens. Also it is meant to stop cavitation while the stat is closed. The solution is to run an external bypass as the factory did through the SU's, or around the front of the head. The other option is to drill a 1/4" hole in the tstat, this is what I will try cause it's easiest 

 

Here's an interesting link http://forums.hybridz.org/index.php/topic/43457-coolant-circulation-bypass-line/page__st__20

[peter mc]

hay mate

why lol your engine runs cool and is low comp you dont need any more cooling on your engine

[Riceburner]

I'm always trying to do something  lol. Yeah temps are fine, but I'd like to make it a long living motor and this mod should help prolong my precious diesel water pump and timing cover by supposedly stopping any cavitation damage occuring while the stat is closed.

 

Not to mention protect that brilliant P90!

[Zedman240®]

I'm running that bypass line and one big positive outcome was the warming up time (as in time when the temp needle started to move) occurred at least 5 mins earlier than without the bypass. I've done it to all my previous zeds and current one.

[peter mc]

hay Gareth ,,, you got me thinking about water and how every one bangs on about the rear cylinders running hot ...

now iv not seen this till now when we tuned the stroker , and made some real power and torque  ,what we seen was no,5 cylinder was hotter and the plug was a lot hotter, and we thought  mmm what should we do and what is the real problem.

well what to do , get a p90 and cut it up and find how it works ,, and thanks to a good man in Tessie who let me cut a head up we found that there was a casting flash that stoped the water from doing its job .

what happens is the water has a very hard time moving from the hottest spots under the chamber to the outlet ,

some people have fitted water outlets on the top of the head  and this helps but does not fix the real problem . It just helps not fix, so how do you fix the real problem  well i came up with this .

this with the bleed hose mod lets the water move aroud the hot spot and the motor runs lots cooler and it come up to temp very fast 

this mod has to be done to all the exhaust ports ,

[Riceburner]

wow, thats quite the discovery Pete! it looks like you drill in and remove some of the excess casting, is that what restricts the flow round the back of the head? It looks really tight in there especially if those ports are opened up!

 

I was thinking the bypass pipe will help stop cavitation destroying my rare and very expensive diesel water pump. On a side note my brother tried the 6mm hole in the Tstat on his 1600, it took forever to warm up and never actually got completely up to temp... And that's on a pretty much stock L20b. Looks like I'll go the bypass pipe around the front and into the pump inlet to start with.

[peter mc]

iv looked at so many fixes for this and none have fixed the problem all just help , but the water has no path from under chamber it has to go thou very small holes some are blocked and the casting stops the path ,

so this mod with 2 dash 6 hoses to the top of the head , and run to the cold side of the pump makes the car come up to temp much faster and the rear runs at the same temp as the front