Hi all. I bought a 1991 F150 302 from a local dealer about 100 days ago (with a 90 day warranty). I have recently had some power and knock problems under load, either when accelerating or upgrade, but only when it is warm outside. So, last night I took a look around the engine compartment and noticed my coolant resevoir was brown. Immediately I get concerned and I look at the oil, which was changed about 4 weeks ago. The oil was totally clean and at the full mark...no signs of telltale foam of a head gasket leak. Transmission fluid is clean also...as I was worried about radiator heat exchanger leak. One thing I did also notice was it does not seem as though my temperature gage ever gets into the "normal" range.
Has anyone else had this problem? Could this be oil in the coolant resevoir? Could it be something else? I'm 10 days out of warranty and the last thing I want now is a major repair...
I have a 92 F150 302 and have had it since it had 10k miles. I'm now up to 130k. I've had the same thing happen to me, but what I found fixed it was using a higher octane fuel and/or adding to each tank a bottle of injector cleaner (ie: STP or other)when it happens. I've also had the radiator water looking brown. Have an engine and radiator system flush done. You might need to have them do it twice. It will help clean out all the deposits that are causing the discolorization and keep your motor running cooler. Hope this helps out.
The brown you see in the coolant tank could be rust, but more likely is stop leak. If you do have it flushed and there is stop leak in there then it may start leaking again. This is what happened to an F-150 that my brother bought from a lot a few years ago.
DannyP
89 F-150 4x4 former EFI I-6 now carbed 351W, Edelbrock heads,cam,intake,carb.
MSD 6A, ZF, Sterling 10.25 with 3.55L's.
