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V8, thermostat Bypass/running without heater hoses?


Steve 90
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Plumbed the coolant hoses in on the V8 today (and got it running, woo hoo :D :D !!) Im not running a heater of any sort so will not be using the heater hoses. I assume that when the thermostat is closed, without the heater hoses there is no way for the water in the block to circulate. Am I right?? or is there some form of built in/internal bypass for this situation (as there was on some of the older cars that had a tap in the heater hose). Ive had a good look round and cant see any way that there would be a bypass so the way I see it is I have a few options, Either

loop the heater hose from the manifold back into the bottom hose?? (would rather not if possible as its more clutter and more hoses to potentially cause problems)

Run with no thermostat, replace it with a restriction plate?? (an option but would warm up be a bit slow?)

or maybe just drill a few bleed holes in the thermostat??? If I was to go down the route of bleed holes in a thermostat, What size would I need to get enough circulation and avoid hot spots.

Anybody have any idea's or experience or even just clarify some of my suspicions?

Cheers.

Steve.

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Genuine stats should have a jiggle pin in the top to prevent airlocks & let a little flow round when closed.

Non-gen ones, even "decent" ones, don't and will give trouble - ask me how I know <_<

...and because of that I can also tell you that if you pull the centre out of the stat it will run too cool (between 40 and 70 degrees in my case) most of the time.

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Steve

If you are talking about the 2 heater pipes that run along the drivers rocker cover to the heater a simple bypass is to

Maintain Thermostata and on the 2 x 3/4 inch pipes simply link them together, job done if that helps ?

nige

I dont have any of that pipework on either engine, Just the pipe sticking out of the front of the manifold just below the thermostat housing in the V. I can simply connect this back into the bottom hose but thought if I could blank it off the less hoses the better. I like keeping things simple and minimalist on the truck if possible.

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I am so tired now can barely think :blink:

From whats left of my memory the 2x pipes are fed from differing outlets.

1 - from a pipe coming out of the inlet manifold, this normally joins pipe 1,and

2 - a hose is connected to the back of the water pump there are normally 2 outlets and one is open and flows, this then is joined to the 2nd pipe

Joining these together is also fine - you don't need the 2 pipes, but its easier to do so, as to going into the bottom hose thats more for the header tank.

However there are also a number of other weird and wonderfull BL varinats, some insane it seems, so unsure which one you have, when we built up Fridges motor he discovered the "Pure Joy" of the various "look the F same but not quite FFS" Options on V8s inc pulleys, pumps fans and these 2 ferkin heater options :)

Nige

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I am so tired now can barely think :blink:

From whats left of my memory the 2x pipes are fed from differing outlets.

1 - from a pipe coming out of the inlet manifold, this normally joins pipe 1,and

2 - a hose is connected to the back of the water pump there are normally 2 outlets and one is open and flows, this then is joined to the 2nd pipe

Joining these together is also fine - you don't need the 2 pipes, but its easier to do so, as to going into the bottom hose thats more for the header tank.

However there are also a number of other weird and wonderfull BL varinats, some insane it seems, so unsure which one you have, when we built up Fridges motor he discovered the "Pure Joy" of the various "look the F same but not quite FFS" Options on V8s inc pulleys, pumps fans and these 2 ferkin heater options :)

Nige

Yep, Mines another variation. As std the one heater hose comes from the manifold then the other runs back alnog the rocker cover then down a steel pipe that twists its way down to the bottom hose. The bottom hose is long gone as mine are all custom for a different rad setup. So in theory I should just be able to run it back into the new bottom hose?? Which I think is probably the answer unless I decide to run without a stat.

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Genuine stats should have a jiggle pin in the top to prevent airlocks & let a little flow round when closed.

Non-gen ones, even "decent" ones, don't and will give trouble - ask me how I know <_<

...and because of that I can also tell you that if you pull the centre out of the stat it will run too cool (between 40 and 70 degrees in my case) most of the time.

Mmm, probably going to take quite a bit of trial and error :huh: to get the right size hole and have it run at a decent temp all year round!

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Also it may be quicker in the long run to take a few pictures of your plumbing so we can see what's going on.

That would be far too sensible :D I did intend taking some pic's but the emotion of getting it running became a little overwhelming (I just had to go for a pint to celebrate) and I forgot. Will get some up tomorrow so you can see what im waffling on about!

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Block the port of in the manifold, ( the one on the drivers side ), and use a standard stat and it'll be fine. There is also a smaller port on the manifold, 1/4" ish bore , leave about 6" of pipe on this and block it off, This is a good point for bleeding the air out of it.

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There is also a smaller port on the manifold, 1/4" ish bore , leave about 6" of pipe on this and block it off, This is a good point for bleeding the air out of it.

Is that the one that usually goes to the bottom of the throttle body?

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Steve,

Doing what you going to do with it you can never have the engine too cold stst wise so fit the early 74 degree stat :)

No stst = cavitation, and a plate with a hole in the middle instead of the stst is "3 bears engineering time" (1st too hot 2nd too cold etc etc) :lol:

Low 74 stst just means fans get to work maybe lesss :)

Nige

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Pump removed from a 3.9 engine showing that water circulates around the lower halves of the engine:

post-7113-1236544724_thumb.jpg

Picture showing the heater pipes - one connecting to the rear of the pump, the other fed from the front of the inlet manfold:

post-7113-1236544827_thumb.jpg

What this implies is that in order to circulate water up to the top of the engine you will need to connect the inlet manifold outlet to the system somewhere otherwise water flow will be restricted to flowing around the lower part of the engine only.

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What this implies is that in order to circulate water up to the top of the engine you will need to connect the inlet manifold outlet to the system somewhere otherwise water flow will be restricted to flowing around the lower part of the engine only.

Erm, aren't there water passages up through the branches of the inlet manifold? :huh:

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There are but air could be trapped up there if pipes like the heater or throttle body pipes are blanked.

Steve

The heater and throttle body pipes are both taken from points in the manifold that are lower than the Thermostat so as long as there is a bleed valve in the stat I cant see air locks being an issue.

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You can see here the feed for the heater from the manifold although I have blocked it off with the gauge sender (two bird with one stone n all that!) and the pipe running along the rocker cover is the other heater hose which just goes back to the bottom hose. Very different to the pre serp' motors.

DSC01077.jpg

And here's a blanker fitted to the manifold where the heater hose would come out if it was a pre serp' engine. If I do run a hose back to the bottom hose I'll make use of this as the routing will be much better than the other.

DSC01078.jpg

Hope its a bit clearer!

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A side question....where are you mounting your coil packs?

Last photo stopped me dead as the dizzy stopper looks just like the one I've just turned up.

Steve

LOL, Dont worry, I made my own, Yours is still there :D

My coil packs are on the Bulkhead. The engine is tucked right back into the bulkhead so the leads didn't need to be any longer to mount them there and that way they are way up away from water and out of the way of getting splashed by the fans etc.

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