3FE overheating issues

[Bryan062087]

I know I'm a 62 guy, but some of yall run 3fe's too so I thought I'd ask.

I've been chasing an annoying overheating problem for a while. Replaced water pump, radiator, thermostat, fan clutch, and flushed the cooling system. Engine runs cool as long as I'm moving at a constant speed but If I'm stopped for a while or driving in the city with lots of traffic lights it creeps up to about 215-220+.

I'd kind of given up on finding the problem (for now), and put in a 180* thermostat just to get through this summer because its so hot here.

Well, last night I picked up a flowmaster catback exhaust from a fellow cruiserhead and had it put on today. With the flowmater catback on, the usual time it took my water temp to creep up to 215+ range has shortened a lot. Now if I stop at just one light, the temp rises to 205+ range in a matter of seconds (10-15) and takes a longer, once moving to come back down. While before with the previous exhaust on, the water temp would stay 190ish unless the traffic was pretty heavy or I was crawling along at 10mph for while.

Old exhaust was 1.75-2inch pipe with toyota style tube? muffler.

Now im running the standard 1.75-2inch pipe until after the cats, then 2.5 inch to the flowmaster and 2.5 inch tailpipe.

Whats going on here? Back pressure drop after the cats isn't pulling the exhaust through the cats fast enough? Clogged cat?

 

[alkaline747trio]

Sounds like a clogged cat. There's no fix but to replace or gut them. If you can still unbolt the cats/down pipes, quick fix/test would be to just remove them and if you can, remove the O2 sensors from them and take a piece of rebar and a hammer and just clean out all the innards. If they were clogged, this will let you know, you'll gain some ponies, and IMO with the 3FE's exhaust routing on the 80 atleast, it creates a pretty cool mustang like echo. If they are/were clogged, you could replace them with magnaflow cats. Very high flowing, and about the cheapest you're going to find.

 

[Nevyn]

Bryan062087 you just described my last few months exactly, My last resort was to pull the radiator and get the core cleaned properly. This I will be doing tonight (and probably will anyway) except that I have not played with my exhaust at all.

I wanted to ask what the end result was, did you gut the CAT and did it solve the problem? Hey at least it is a free fix with the added bonus of a "pretty cool mustang like echo"

 

[slow91fj90]

over heating

I had the same issue with my 91, I got some header wrap from summit and wraped exhaust from manifold collector down to cats, no more heat issues.

 

[Bryan062087]

Interesting... Thanks for the info. You dug this thread out of the depths.

I finally swapped in a 180 degree thermostat to get me through the rest of the summer, but I still haven't solved the overheating issue. Now that its cold, my water temp stays 180-190. But I know I've still got an issue somewhere, idling makes the water temp move up to 190 and when I'm moving its back down to 180.

I may end up trying the heat wrap stuff. Thanks. Seems like it should cool properly without it though because it wasn't on there stock.