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Primerdimer

521 no radiator flow

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I have a 521 with a stock L16.

So I just flushed my radiator and engine and put a new thermostat in. The thermostat I pulled out was a 160 degree and I put a 180 in as this is what my manual said it calls for. After putting it in, I was noticing there was no flow looking down into the radiator, even after letting it heat up for like 10 min. So I pulled the thermostat out and tried again without it. This time it was flowing, so in my head, that meant the thermostat was the culprit. So I went to buy a new one, this time a better quality one (I hope at least, it was 11 bucks). Put it in, same thing.
 

Am I just not letting it warm up long enough?

Will there be zero flow up until the point that it opens?

Is this thermostat maybe too high in temp and my engine isn’t making it there?

 

Sorry I don’t fully understand how the cooling system operates just yet. Seems like I’ll know by the end of this tho haha... thanks 

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 On a stock l16, there is not a factory bypass for the thermostat.  My fix was to shoot three small holes in my thermostat, so that a water can flow past the thermostat and keep you from having a cool pocket of water by the thermostat.  

 

 

I will search for a thread.

 

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7 minutes ago, bilzbobaggins said:

 On a stock l16, there is not a factory bypass for the thermostat.  My fix was to shoot three small holes in my thermostat, so that a water can flow past the thermostat and keep you from having a cool pocket of water by the thermostat.  

 

 

I will search for a thread.

 

So this is just normal? Should I let it warm up longer?

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Were you having any problems before you flushed and replaced the thermostat?  Does your replacement thermostat have a jiggle valve in it?  I cant seem to find one good  thread about this that still has photos. Still searching.

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5 minutes ago, bilzbobaggins said:

Were you having any problems before you flushed and replaced the thermostat?  Does your replacement thermostat have a jiggle valve in it?  I cant seem to find one good  thread about this that still has photos. Still searching.

No I wasn’t having issues. I’m not sure what a jiggle valve is but if it’s like a little tiny piece of loose copper, than yea, pretty sure. What’s that for to let some go by? 

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2 minutes ago, Primerdimer said:

No I wasn’t having issues. I’m not sure what a jiggle valve is but if it’s like a little tiny piece of loose copper, than yea, pretty sure. What’s that for to let some go by? 

 

Yeah, it lets some water flow past the thermostat to keep from having a cooler pocket of water right up on the thermostat.  Some folks pop that out and open it up bigger.  I just drilled three small holes in the outer edge of mine to promote flow.\

 

 

Go to google.  Type in "ratsun" l16 no cooling bypass.  Or anything you wanna find on ratsun.  Not being passive aggressive, its just the best way to search. and find out the info.

Edited by bilzbobaggins
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Look at post number 11 on this thread.  Its waynos.  Best description I can find.  I can think stuff in my head but find it hard to type it out.

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3 minutes ago, bilzbobaggins said:

 

 

Look at post number 11 on this thread.  Its waynos.  Best description I can find.  I can think stuff in my head but find it hard to type it out.

That’s great, thanks a lot! Gonna pull it out and drill some holes!

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I would have left the 160 in there as there was no proplem before. Was it over heating? if not then there was not proplem

it hard to see flow as most times the stat opens for a short time then closes back up.

depending on year of 521 there is a bypass from the intake manifold heater line to the lower that housing.

I drill a 1/8 hole that's it if needed.

the only good 3 core out there is a KOYO(made in Indonesia) or a old Modine Brass Modine that was converted to a 3 core.

 

my Chinese 3 core leaks like a motherfucker if I install a 180 stat. run a160 its fine. I don't get it. also all need a 1/4 washer to space the rad off the core support otherwise don't fit right. Even the KOYO

 

 

get a bottle of anti seize as it will be your friend and use it. esp on the stat bolts make sure dry and put it on keeps from rusting also.  water pump bolt intake exhaust ect…… don't be cheap

Edited by banzai510(hainz)
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I wrote these guys a long time ago

If one sends in there old one they can clone it plus MADE IN USA and no epoxy. but expensive

But I notice the flange is also flush which would need a spacer (maybe / I don't know)  remember the 510/521 the core is set back to not hit the top of the core support

 

https://wizardcooling.com/search.php?search_query=datsun&section=product

these guys in NewYork so the east coast guys it will be cheaper to send in your old rad to clone it 

Edited by banzai510(hainz)

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Run a 180. If there is over heating problems it isn't the thermostat. The L16 should idle or run all day and night without problems. Previous owners fix problems by masking them, like a 160F thermostat. Gauge should run roughly in the middle of the 'run range'. The L16 is designed to give best performance, economy and longevity with the engine operating at 180F. 

 

You only need ONE hole about 1/8". If you drill more you might as well take the thermostat out altogether. First make sure there is not a small fitting on the side or front of the thermostat housing with a small 3/8" hose and pipe going down to the lower rad hose. If it has this connection you don't need holes in your thermostat.

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When I have concerns about flow and temp, I let the car idle without the radiator cap on and let it come up to temp. Go buy yourself a meat thermometer (or something similar that will go up to 230F or thereabouts) and put the thermometer in the radiator filler neck while you're letting it come up to temp. Once the engine gets warm enough, the t-stat should open and start flowing coolant, and it should show on the thermometer. If the engine runs for a very long time and the t-stat never opens, then there is a problem. If the temp gauge in the dash works, check this too while you're letting it come up to temp.

 

I always snip off the jiggle valve when installing a new t-stat. This will allow a tiny bit of coolant flow. Better than that is to drill the jiggle valve hole to 1/4".

 

To check a t-stat, put it in a pot of water on your stove top and heat it up. Once the water comes up to temp, the t-stat should open. If it does not open by the time the water boils, it's not good (unless of course it is a very high temp t-stat, which come in a lot of newer cars). NEVER heat a t-stat with a torch! I did this once when I was a kid, and it blew up in my face!

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3 hours ago, datzenmike said:

Run a 180. If there is over heating problems it isn't the thermostat. The L16 should idle or run all day and night without problems. Previous owners fix problems by masking them, like a 160F thermostat. Gauge should run roughly in the middle of the 'run range'. The L16 is designed to give best performance, economy and longevity with the engine operating at 180F. 

 

You only need ONE hole about 1/8". If you drill more you might as well take the thermostat out altogether. First make sure there is not a small fitting on the side or front of the thermostat housing with a small 3/8" hose and pipe going down to the lower rad hose. If it has this connection you don't need holes in your thermostat.

 

If the later bypass hose is 3/8, why not drill three 1/8" holes in it?  Or am I not thinking of factor to toss into my thinking?

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The by pass water volume doesn't matter because it gets sent right back into the inlet of the pump and back into the warming engine. If you drill a hole larger than 1/8 you're pumping water into the rad which displaces an equal amount of cold water into the cold engine. It's like having a thermostat that doesn't close properly. Putting cold water into a cold engine that is trying to warm up is nonsense and slows the warm up. If I didn't have a bypass I would drill and tap for a fitting and connect it to the hose from the intake runners.

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That by-pass fitting Datsun put into the thermostat housing is a 1/4" hole Mike and it is right there at the thermostat, the hot coolant has to go thru the thermostat spring to get to the by-pass, I have said before that is a lot of coolant by-passing but it seems to work just fine and my windshield stays clear and doesn't fog up anymore once the engine is warmed up.

I agree with Mike about the drilling and tapping the L16 thermostat housing as there is a place to drill it on the side, it really should not be that hard to do if you cannot find an L20b housing with the by-pass already in it.

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Like I said the volume doesn't really matter as it goes directly back into the engine. You would not want it too large, because in hot weather this is water NOT going through the rad. Just enough so the thermostat can sample the temperature of the coolant from deep inside the engine. There is a line already there from the intake runners so easy enough to join it in. Only L20Bs from '75-'77 didn't have the water cooled/warmed intakes.

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Just take note if water come out of spark plug if open could be loose bolts not clamping on the intake gasket and sucking water into the intake.

sont over think this 

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Ok, so now that I am getting back to this, I’ve already gone and drilled 1/8” holes in the t-stat... 4 of them! Dang it. Now I’m reading this and it seems that’s not the right move. I think I’m just going to hunt down an L20 housing and go that route. I’m sure I could drill and tap a hole in the side of mine if I can’t find one, too. The only problem I should be experiencing from all these holes now is a slow warm up, right? My coolant gauge on my cluster doesn’t seem to work very great. The farthest I’ve seen it come up was maybe a 1/4 - 3/8” and its intermittent. Most the time it’s all the way left. Another thing I need to address... anyone have a way to test the temp sender? 

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Living in Long Beach, you shouldn't have any problems with slow heating. If it's already installed, leave it.

 

Gauges not working properly can be caused by many things, but on older electronic gauges, it's usually resistance related, ie- bad grounds, corroded connections, loose windings in the gauge, old brittle wires, etc. A simple cleaning of the gauge and the connections may bring it back to life.

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I would agree, just leave it in there till you find a thermostat housing and cover with a by-pass and associated by-pass piping, buy it all at once so you know it is complete. 

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