A couple su related questions

[Just Joel]

I've been researching this for a while and need a definitive answer so i can move forward with the project... after installing the su manifold, I realized right away that I don't have enogh room for the standard coolant bypass at the bottom of the thermostat housing. Now, I've read that i can eliminate this line and just drill and 1/8" hile in the thermostat but I'm looking for confirmation that this will work without issue. What are you su users doing? Also, what are you guys using for the crank case breather to pcv hose on su's? Does the origonal single downdraft hose work (I dont currently have one or I would check)

 

Thanks

Joel

[ggzilla]

Are you asking about an L20B? Because they had some overheating complaints and increased the size of the hose according to the TSB.

 

I've seen other L-series engines without the hose connection.

[Z chopper]

ya which engine?

[wayno]

I've been researching this for a while and need a definitive answer so i can move forward with the project... after installing the su manifold, I realized right away that I don't have enogh room for the standard coolant bypass at the bottom of the thermostat housing. Now, I've read that i can eliminate this line and just drill and 1/8" hile in the thermostat but I'm looking for confirmation that this will work without issue. What are you su users doing? Also, what are you guys using for the crank case breather to pcv hose on su's? Does the origonal single downdraft hose work (I dont currently have one or I would check)

 

Thanks

Joel

 

 

I am baffled by this, I have dual SUs and have all the bypass hoses needed, drilling a hole in the thermostat is just a jury rig. Does you SU intake manifold have the water inlet on the front radiator side runner? Does your head not have the holes for the intake manifold water jacket? I drilled my head, used the intake gasket to drill them in the proper place.

I am using the stock L20b crankcase tube, then have the stock hose, then I spliced in another hose to get to the PCV, been there for 15 years so far, it's not pretty, I went for function.

[Just Joel]

Sorry, I'm working on an l20b... connecting the intake is not the issue, I'm talking about the small u shaped line located on the hardline that comes from the water pump outlet to the thermostat housing. If drilling a hole is not the fix, then what did the factory coolant hardline for the su's look like? Does anyone have a pic for reference?

 

Thanks

joel

[Just Joel]

Oh and i have modified the the crank case breather to exit in the same location as a factory l16... is there a factory hose for this application or do i need ro rig something?

 

Thanks

Joel

[ggzilla]

They looked like the early L16s IIRC, no coolant line. The L20B always used the coolant hose-fitted housing, and was never offered in Twin carb version like the L16T and L18T.

[datzenmike]

Her's my K14 SU intake.

 

 

The PCV is the black braided hose in the middle. The manifold coolant outlet is far right inside that circle of rubber hose. I was going to put on my L18 but instead it will likely be on my U-67 head L20B. If so I will drill the coolant lines out in that head and modify the thermostat housing return line.

 

 

I'm talking about the small u shaped line located on the hardline that comes from the water pump outlet to the thermostat housing. If drilling a hole is not the fix, then what did the factory coolant hardline for the su's look like? Does anyone have a pic for reference?

 

Thanks

joel

 

To be clear, water flow is from the head through the manifold and to a hard line flowing from the thermostat housing to the inlet or return to the water pump.

 

Water in the manifold simply keeps the temperature of the intake air more constant. In a way it warms the cold air and cools it when there is excessive radiant heat form the nearby exhaust.

 

If you have a '75-'77 L20B (likely with a U-67 head) the intake was not cooled/warmed by coolant passages and the coolant line will only run from the thermostat housing back down to the lower rad hose inlet to the water pump. You will need to find or use one from an earlier L18/18 or any L20B from '78 on that did have manifold cooling.

 

Yes you can leave it off but there is a reason all SUs have a heat shield to shield the carbs and manifold. They get hot! Only makes sense to have the coolant working as well.

 

If there is a return line from the thermostat housing you shouldn't need to drill a hole in the thermostat itself but if you do make it 1/8".

[Just Joel]

I am baffled by this, I have dual SUs and have all the bypass hoses needed, drilling a hole in the thermostat is just a jury rig. Does you SU intake manifold have the water inlet on the front radiator side runner? Does your head not have the holes for the intake manifold water jacket? I drilled my head, used the intake gasket to drill them in the proper place.

I am using the stock L20b crankcase tube, then have the stock hose, then I spliced in another hose to get to the PCV, been there for 15 years so far, it's not pretty, I went for function.

 

Pics of your setup?

[Sealik]

Pics of your setup?

 

 

Here'[s some....

 

http://community.ratsun.net/topic/28984-sus-setups/page__hl__%2Bclean+%2Bsus

[zerow]

I am running the hose at the water pump outlet. You have to find the coolant hardline that runs around the front of the block towards the thermostat housing if you plan to run this. You will have to slightly flare the end closest to the water pump for the line to work. I am also running the coolant bypass line on the SU manifold. If needed, I can get some pictures to help you out. Just let me know :)

[Just Joel]

Here'[s some....

 

http://community.ratsun.net/topic/28984-sus-setups/page__hl__%2Bclean+%2Bsus

 

Good stuff... i remeber seeing this thread at one point. From the pictures, I can see that a couple of the setups run the thermostat bypass by rigging it to work and quite a few don't run it at all. I'm not sure what the one's without are doing (must have drilled the small hole in the thermostat? ) but at this point I think I'm going to have to figure out a way to retain the thermostat bypass hose off the intake coolant line as i don't see a definitive alternative. What was the stock solution for su equipped Datsuns? I have noticed the longer intake manifold coolant hard line but other than that, the front hard line running around the head looks the same just shorter and without the "t" for the thermastat bypass line... sorry, this one is hard to explain.

 

Thanks

Joel

[Just Joel]

I am running the hose at the water pump outlet. You have to find the coolant hardline that runs around the front of the block towards the thermostat housing if you've plan to run this. You will have to slightly flare the end closest to the water pump for the line to work. I am also running the coolant bypass line on the SU manifold. If needed, I can get some pictures to help you out. Just let me know :)

 

I plan to run the line around the head, I'm just talking about the "t" in that line and the "u" shaped hose that runs to the bottom half of the thermostat housing.

 

Thanks

Joel

[Sealik]

I plan to run the line around the head, I'm just talking about the "t" in that line and the "u" shaped hose that runs to the bottom half of the thermostat housing.

 

Thanks

Joel

 

 

 

 

The hose hanging down went to the intake

 

[Just Joel]

Ok, I see it there... so basically I just need to figure out a clean way of maintaining that connection...

[Sealik]

I'm in the midst of swapping to SUs.

You can see the coolant hardline coming out the front of the IM...now I have to route/tee that in and drill holes in the side of the head...etc.

 

 

I'm wondering if that brass plug on the side of the thermostat housing can be plumbed into the scheme of things...I don't think so though.

 

Actually...I think you can hook that up to the IM.

Fitting is below thermostat and coolant will bypass when engine is cold

Edited December 27, 2011 by Sealik

[wayno]

These are photos of my setup concerning the thermostat water lines.

Line coming off thermostat housing below upper radiator hose.

Line from thermostat housing to tee in front of head.

Water line making turn from front of head, going under fuel pump.

Line going into water pump inlet on passinger side.

Hose coming from thermostat housing to tee, differant angle, the line continues to the intake manifold.

[Sealik]

These are photos of my setup concerning the thermostat water lines.

 

Wayno...no vacuum advance hose to dizzy?

 

Anywho....instead of teeing off...one could utilize that brass plug (side of housing) to the IM

[wayno]

Wayno...no vacuum advance hose to dizzy?

 

Anywho....instead of teeing off...one could utilize that brass plug (side of housing) to the IM

 

 

The vacuum hose was in the way of the photo.

Fact is, I am not sure how this setup makes the water tempreture stable, but it does, as when I was using the L16 lower thermostat housing without the bypass hose, my water temp. was all over the place, and it even over heated once. I put the messy L20b housing on with the bypass and all my problems went away.

[Sealik]

The vacuum hose was in the way of the photo.

Fact is, I am not sure how this setup makes the water tempreture stable, but it does, as when I was using the L16 lower thermostat housing without the bypass hose, my water temp. was all over the place, and it even over heated once. I put the messy L20b housing on with the bypass and all my problems went away.

 

 

Ahhhhh...I see...prepping for the photo shoot.... :D

I think I'll utilize the brass plug for the bypass to the IM

[datzenmike]

That's because the thermostat housing is outside the head and the cold water is trapped in there while the rest of the motor heats up. A return line (or a small hole drilled in the thermostat) allows warm water to be drawn from the head/block and flow past the thermostat so it can react to the temp.

 

It's routed to the pump inlet instead of the top rad so that it does not slow the warm up.

[wayno]

Ahhhhh...I see...prepping for the photo shoot.... :D

I think I'll utilize the brass plug for the bypass to the IM

 

I am just using the stock bypass setup off my L20b engine, as I said, I don't understand how it works, it just does. You can test it that way and give us feedback on what your water temp. acts like piped that way.

[Sealik]

I am just using the stock bypass setup off my L20b engine, as I said, I don't understand how it works, it just does. You can test it that way and give us feedback on what your water temp. acts like piped that way.

 

It should work exactly the same.....just 'teeing' it off a little farther down the line...so to speak....(I think... :D )

I've got a PS idler pully/bracket mounted in that locale....not too much room to work with

[wayno]

It should work exactly the same.....just 'teeing' it off a little farther down the line...so to speak....(I think... :D )

I've got a PS idler pully/bracket mounted in that locale....not too much room to work with

 

Power steering for an L20b, is it stock? I would like to see photos of that, or is it just napZ stuff bolted on despite the L20b timing chain cover and differances in the head?

[datzenmike]

 

Anywho....instead of teeing off...one could utilize that brass plug (side of housing) to the IM

 

Connecting the IM to that brass plug won't allow any flow (both are connected to the head) it will need to be spliced into the line going down to the lower rad inlet.