The Chrysler swap has always run a little warmer than I liked. The engine runs a 180deg thermostat, but even with an aluminum 3 core radiator, I could never get it to run under 197deg. I never really looked too closely at the pipes until now.....and this is what I find:
Both pipes are bent up and kinked. The right side pipe was also dented on the bottom under the kink and up by the front. It looks like someone lifted the car by the coolant pipe. I cut the right side pipe open to see how bad it really was:
I cant believe the engine only ran warm and didn't overheat! Luckily I found a couple used pipes in good condition to replace these. I'll update with more pics when I get it put back together.
Rather than throw your old ones away, you can salvage them now that you have inside access to the crunched area. Put the two pieces back together and scribe an index mark on both. You can then open up the two pieces, put them back together by matching up the index marks and having them tig welded.
Yours is a good example of why you should carry copies of the Fiero lift points in your car and hand it to the shop anytime it goes on a lift. A Pontiac dealer did one of my cars, but not as bad. The aero rocker panel took most of the damage.
Well it appears that the crushed cooling pipes were only part of my issue and not the root cause. After replacing both pipes, the problem of the engine running too warm still exists......much to my chagrin! I'm still 197+ on the highway! Factory t-stat was supposed to be 180deg. After testing my stat on the stove using a thermometer and a pot of water, I discovered my 180 stat didn't even begin to lift off the seat til 192 deg, and even with the water at 210deg, the stat was only open half way. I decided to run without a stat and see what happens. After a 5 mile test drive at 55mph, coolant temp settles in at about 165deg......I think I'm gonna leave the t-stat out for a while til I can get a few more miles of data.
[This message has been edited by seajai (edited 06-08-2014).]
The engine has the thermostat mounted on the waterpump inlet instead of the outlet like normal. Because of this, coolant needs a bypass when the stat is closed, this is handled by the heater core circuit. There is also a bypass from the outlet, through the coolant tank and back to the inlet. Additionally there is an internal bypass to bathe the thermostat in hot coolant so it will open. There is a problem with some of these engines overheating when the cooling fans come on because the internal bypass passage gets blocked with scale and the cold coolant coming in from the radiator causes the stat to close too soon. I think the heater circuit helped with cooling because when I blocked it off, the engine ran hotter.
Not sure how applicable this is to all Fieros (due to engine swaps, and technology at time of factory engine), but running a t-stat that is too LOW in temp, can have a significant impact on fuel economy and performance. When the coolant does not reach the parameters of the designed operation temp, the computer essentially thinks the engine has not warmed up. It then dumps more fuel in the engine (like a choke) to help bring the temp up more quickly. We learned this on our 502 Dually. Since we pull a 53' trailer, we wanted to keep engine temps down. We swapped in a low temp t-stat and went from about 10mpg to 6! Chased that issue for quite a while. As soon as I put back in the proper t-stat, idle improved, MPG went back to normal....
Yeah, I was reading about too low of a stat on the 300m forum and people were experiencing the same issues. Plus the Chrysler PCM will set a code if the coolant temperature is too low. I did notice that the engine warmed up quite slowly when on yhe highway so I'll probably end up installing an OEM Chrysler stat.