Cooling issue/Internal Thermostat Conversion by PO?

[beachspider]

So my '79 has just started running too warm and I've noticed the fan hasn't come on. I was about to check the thermostat expecting to see an external unit. But my car has only two hoses and no upper hose on passenger's side. I suspect this to be a conversion to a internal thermostat as I understand the internal system wasn't used on later model Spiders. From what I've read here, I understand the external system works better so am thinking about changing it back. Any reason why I shouldn't? What do I need besides the three hoses and the right thermostat? Does the fitting at the top need to be replaced? By doing so I will be removing the internal thermostat, right?

http://www.flickr.com/photos/93172121@N05/8471901401/

[BEEK]

there is absolutly nothing wrong with the internal thermostat, it is much cheaper and works just fine. your fan sending unit is probably bad

[So Cal Mark]

we have different opinions on the t-stats, I prefer the external stats. By design, they flow more

[BEEK]

mark, my only argument to that is. do the engines overheat or not flow enough with a head mounted thermostat? i do kind of like the bypass feature during warm up as opposed to no flow. and granted in my race car applications we dont use a thermostat at all, we use a reducer to limit the flow of water to reach proper operating temperatures. and even with a stock radiator that opening is quite small. 3/4" or so.. just my opinion... i am not a million dollar engineer

[So Cal Mark]

When Fiat increased the engine size to 1800 they went to the external stat. That's also when the radiators got larger. I haven't researched the larger motors with internal stats so I'm deferring to Fiat's engineers and their desire for better cooling. I've been reading about water pump impeller and t-stat design from an engineering standpoint, and I believe the external stats are a better way to go.
The other issue I see is the weakness of the water outlet threads. I can't tell you how many cars I get in with stripped threads in that location.

[BEEK]

mark, as i recall, the earlier spiders used the external thermostat too. it was just 73-74 that used internals, as best i remember

[beachspider]

Thanks for all the advice. Though I'd really like to support Spider specific merchants, I am thinking about picking up a thermostat locally to get it going for the weekend. On Napa's site, searching for a thermostat for a '73 Spider, I came up with part number THM 170. Will this work in this set-up?

Following that, because I really do like the idea of more flow and keeping it as original as possible, I'm still thinking about changing it over, at which time I will use one of our valued vendors. Wondering if anyone could tell me if, by looking at my photo, the t-fitting on top is the right one but just retrofitted for the conversion. I can see an outline of where a hose once was. There is a screw holding what I'm guessing is a plate and seal to close off the passenger side outlet. Is this correct? Also, is it likely that the water pump was also changed out?

[beachspider]

Searching International-Auto's site, they do list a water pump in stock for my '79 but not one for the '73 so I assume either the PO kept the original but it is the wrong pump or replaced it. Sound logic?

[BEEK]

if you want to keep an inhead thermostat i recommend 180 degree. you can buy one that fits a small block chevrolet, real ez, buy one that has a bleed valve, which lets out any trapped air

[beachspider]

And Bayless lists the following water pumps: item #5882684 for '70-'73 Spiders/Coupes and #4314160 for '75-'85 124s. So obviously it should have a different pump, but is it possible the PO owner didn't install the right one with the conversion?

[beachspider]

Napa listing of that part number says its OEM specified temperature, 180 degrees. Not sure about the bleed valve.

[bobplyler]

I'm not sure you would have to change the water pump. The pump still has only one hose coming out of it. Instead of going to the thermostat, it could just go to the radiator.

[BEEK]

agreed, there are 2 different depths of waterpumps on a 124, not counting the early 1438 with fan, the difference is the pulley mount height from the housing, there is an early and a late version, from what i remember 1592, 1756 and 1995 all use the same pump, the 1608 may use the same as well, but there is a version which uses a deeper pulley, it may be 1438 and pushrod only , im not sure

[supplyguy]

Holy crap - photo is almost identical to my engine. I am hoping to switch to single coolant outlet and install internal thermostat (currently missing) for no other reason than the setup I inherited looks goofy. Last summer, my first for my 71, I had no real cooling challenges even during stop and go 90 degree weather (except for the climb to Wintergreen for FFO, which damned near overheated me AND my car).

[manoa matt]

This may help sort out the pumps and pullys http://www.millersmule.com/File%20Libra ... 0Guide.pdf