Cooling system issues AGAIN! (Long)

[Turbofiat124]

Why is the cooling system on 124 Spiders so fussy? I've owned this car for 25 years and the #1 issue that has plagued this car literally from the day I bought it is the cooling system. Either:

1) At idle: The fan kicks on halfway between 190F and 260F
2) At idle : The fan won't kick on at all despite nothing being wrong with the fan, fuse or fan switch
3) Engine temp is normal once it hits 190F then after 5 miles, engine temperature get's progressively hotter (while moving)
4) Radiator fan won't kick on after topping off and bleeding cooling system. Engine overheats within a few minutes. This requires letting is cool down for about 30 minutes then, opening the bleeder screw and topping off again. Air get's trapped something in the system (lower radiator hose going to thermostat perhaps?)

I used to have issues with fan switches failing but since then I installed a relay then later a SPAL fan which pulls less current. So that issue is a thing of the past.

Yesterday I drove the car to work and it did not overheat but I have noticed here recently that it tends to run a bit hotter than it should. Coming home this morning condition #3 arose. When I got home the temperature gauge was almost in the red. I grabbed for my infrared heat pen and started checking temperatures at the head to see if the gauge was telling me a lie or the temperature really was that high. The temperatures were all over the place but the hottest point was 215F.

I tend to think the temperature sensors on these gauges are calibrated to 195F/90C. So below or above that does not necessarily indicate the actual temperature. Where if the gauge is showing 240F, the real temperature could be as low as 215F.

I could here boiling inside the overflow tank and a gurgling sound from the radiator cap. After I woke up I checked the level in the overflow tank and it was bone dry but there was level in the radiator. I don't think I have a leak. I think when I replaced the cambox gasket a couple of years ago I may not have gotten all the air out of the system and over time, as the system burps, it pulls in whatever coolant it needs. However if the tank goes empty, it seems to pull air into the system and cause air pockets . A theory of mine.

Homemade coolant expansion tank:



I had this same thing happen about 10 years ago. In that case, I swapped radiator caps and it seemed to corrected the problem.

I have also had issues where the fan won't kick on until halfway between normal and overheating. Same in this case. I changed the cap and the problem was resolved.

When there used to be radiator shops, I took several of these caps I had collected and had them tested. They all checked out fine.

One theory is over time, funk will buildup between the seal and neck in the radiator possibly not causing a seal which causes the cooling system to not be fully pressurized. Maybe the caps are not actually failing but rather installing a new cap which is clean fixes the problem.

Funk buildup on seal:



But no buildup in the neck:



At one time I thought those Stant #13 caps caused problems but I don't think so.

Fiat 11# versus 13# cap:



I've been using this funnel with success at bleeding the cooling system:



https://www.amazon.com/Lisle-24610-Spil ... B001A4EAV0

So I'm trying to get an understanding at why Fiat Spider cooling systems are so fussy. As far as I know, my 98 Chevy van with 145,000 miles still has the original radiator cap and I know for a fact my 2003 Subaru with 78K miles on it has the original cap and both of these vehicles has never had any cooling issues.

I bet if I top the overflow tank off, clean the gasket in the old cap and neck and start the engine, eventually when the engine hits 190F, the fan will kick on.

I might need to burp the cooling system again.

Any ideas what is going on with these cars?

[4uall]

I discovered a hidden tstat in mine

http://www.fiatspider.com/f15/viewtopic ... verheating

[Turbofiat124]

I've owned this car for 25 years and it's never had an in-head thermostat.

[So Cal Mark]

if you continually get air in the cooling system I'd look into a possible head gasket leak

[Turbofiat124]

if you continually get air in the cooling system I'd look into a possible head gasket leak

Right now I'm leaning toward air getting sucked into the cooling system because the overflow tank went empty. I topped it off after replacing the cambox to head gasket but think overtime some of the coolant has either evaporated or there was a small amount of air still left inside the head and eventually it got sucked into the engine.

The reason I went with this homemade coolant recovery tank from a Marvel's Mystery oil can was the first turbo system used an external wastegate and conflicted with the original tank. When I built the second system, I just kept the tank because I thought it looked cool.

The downside is, it only holds a quart of coolant and I have to use a dipstick to check the level. I've been meaning to solder some brass elbows into the side and connect them with a piece of poly tubing so I can check the level but have not gotten around to it yet.

[spider2081]

Right now I'm leaning toward air getting sucked into the cooling system because the overflow tank went empty.

I think you are correct if the overflow tank was empty then air can get into system. I believe the original overflow tank has a spike like tube in it. When the car cools down it draws water back into the cooling system by siphoning from the overflow back into the cooling system. The original tube has small holes in it so it draws the coolant about 1 inch above the bottom of the tank so it does not pick up the sediment from the tank. If the coolant in the stock tank goes below the top hole in that spike in the tank it too will draw air into the cooling system. Also I believe the original overflow tank cap has an air vent to allow free flow of the siphon effect. It is the coolant level in the tank always being above the spike top hole that blocks air from getting into the coolant system. Maybe you could fabricate a float with an indicator that passes through the cap like early gas gauges.

[RRoller123]

+1, the level in the tank must stay above the top of the needle\spike in the tank. If not, air gets pulled in when the coolant cools and shrinks.

[Turbofiat124]

I had not had a chance to look at my Spider until today. I poured about 3 cups or 750 ml of coolant into the flush tee until coolant bubbled from the bleeder port. That was quite a bit!

I left my no-spill funnel attached while the engine was heating up. While the engine was heating up, I did not notice any bubbles coming up through the funnel. I don't know if that's a good sign I don't have a blown head gasket or it doesn't matter. Eventually I did see a little bit when the fan finally kicked on but by that time the engine was at normal operating temperature. But I have seen this before on other cars I've used the funnel on.

I shut the engine off and replaced the radiator cap and started the car again and let the fan cycle several more times (about 30 minutes) and topped off the recovery tank. I let the engine cool down and used a dowel rod as a dipstick and marked the level and will monitor.

I found a spare recovery tank in my storage building but could not find the bracket to go with it. I know that the original tank is in the barn loft, along with all the non-aspirated parts I removed when i built my first turbo system so at least I know where a bracket is.

But I felt some coolant underneath the tank and maybe around the seam at the bottom. So I'm thinking maybe my homemade recovery tank has a slight leak in it. So I maybe loosing coolant from the recovery tank itself.

[Turbofiat124]

When I got off work I checked the level in the overflow tank and the level seemed roughly the same but then I noticed antifreeze on the splash pan and fan of the grill. I don't know if this was where I had installed the radiator cap and some coolant ran down the radiator or I've got a pin hole leak. I did not notice any puddling between the core and lower cap. Usually if there is a leak it will show up here.

I did not have time to fully spray the engine compartment down.

Before leaving for work today I sprayed the fan and splash pan down with water from a spray bottle and will check when I get off work to see if it's still there. It was dark this morning so I did have time to get the water hose out.

So right now I'm leaning toward a small leak in the radiator.

This radiator came from a parts car and I had it repaired in 1998 and has been sitting in my barn loft since 2010. I had an issue where the car would run hot on the interstate. That turned out to be my Italian licence plate acting as an air damn. So I installed this radiator.

By the way. There are no good radiator repair shops left in town. I could replace it with a new one but seems to me aluminum would be a better choice because it's seems aluminum is less likely to corroded than copper or brass. Simply because my van is almost 20 years old, has 145,000 miles on it and has the original radiator. Doesn't leak and cools just fine.

So I could either buy a new brass/copper radiator, a replacement aluminum radiator (someone was building them a few years ago) or look for a radiator from a modern car. Modern radiators run about $75. Well at least for my Subaru.

I thought about looking into a aluminum/plastic radiator from a modern car. The trouble is most modern radiators are about half as thick and I don't know if it would cool on a Spider. The one on my Subaru is about 1" thick and I have no idea how it manages to keep a 2.5 liter engine cool. Unless it's just longer and taller.

Another issue is the snouts are usually on the opposite ends. So some long piping maybe required.

[seabeelt]

All of the vendors have Radiators. Allison's has new aluminum ones. However none of them are in the$75 range
R/

[Turbofiat124]

Found the source of the leak!

Last night I got out my spray bottle and hosed off the splash pan. This morning the water had dried. When I got to work, I popped the hood after driving the car and once again noticed coolant on the splash pan and the back of my SPAL radiator in the same area. But no coolant at the base of the radiator where the core and lower cap meet.

So I got out my flashlight and started looking about and there is was: The coolant temperature sensor in the upper hose TEE was coated with antifreeze! So it was blowing coolant forward. I guess the reason I did not see it until now was by the time I got around to checking it, the engine had cooled down and the sensor had dried off.

I wouldn't have suspected the leak from this sensor. I have not disturbed or removed the sensor but I guess the copper washer or aluminium tee may have developed some corrosion over time perhaps? Or maybe the sensor itself is busted and is leaking. Good news, they are less than $25.

However about a year ago I was having these misfire issues that I could not seem to track down then discovered as long as the hood was up, the car ran fine but as soon as I shut the hood the car started running rough and discovered this:



So I cleaned off the corrosion on the pins of the sensor and replaced the connector. So maybe wiggling the connector off loosened it?

I'm going to tighten it up when I get off work and if that doesn't fix it, sand the mating surfaces and replace the copper gasket.

This sensor has been the only real source of trouble on the fuel injection system. This makes the second time I've replaced the connector due to corrosion or frayed wires (can't remember the first time). Although it's on the underside of the tee, it's still near the hood. It's below the bleeder screw so if there is any leakage there, coolant drips onto the sensor and causes corrosion.

Also, I once bought an 82 Spider that did not run and turns out the connector had somehow popped off the sensor causing the engine to run rich which fouled the spark plugs. And I've heard of this happening to other Spiders. What's weird is usually I have to wiggle and just about break the connector to get it off so it's odd that particular connector can pop off for no apparent reason.

I'll probably have to check this out for myself on a spare engine I have (unless someone knows right off hand) but I thought about moving the FI coolant temperature sensor in place of the overheat switch at the back of the cylinder head. That is if the overheat switch and the sensor use the same size and thread pitch. Something like M16 X 1.5.

All I'd need to do is solder an extra length of wires in between the ECU and connector. If the sensor will fit this hole.

[Turbofiat124]

When I got off work I took a second look. it appears as though it's the sensor itself that is leaking and not the copper gasket. I started the engine and observed the sensor and noticed coolant leaking from the end of the sensor where the connector plugs in and not the O-ring!

I seem to recall oil pressure light switches and possible oil pressure sending units doing this but have never know a coolant temperature sensor on the fuel injection system spring a leak. Perhaps the plastic or epoxy that is poured into the sensor has cracked. Well you can't expect a 36 year old part to last forever!

I stopped by O'Reily's autoparts on the way home from work and picked one up for $25. I have not installed it yet. I got up a bit too late this morning (the shower felt good....) so I drove my Trabbi instead.