Brown paste under radiator cap

I found, for the first time, a brown pasty substance under the radiator cap and inlet as well as in the reservoir tank of my '88 Colony Park.It did not feel oily to touch and did not float on the coolant.My radiator coolant level is up to the top, and the oil on the dipstick is clean.No goop under the oil filler cap. Car not overheating in traffic with AC on ( in 45 C outside temp). I always use the green coolant, and never mix brands or types. Car moves and accelerates well.No white smoke from the exhaust.
I also noticed that the rubber part of the radiator cap was all peeling away.

Is this just accumulated sludge that can be fixed with flushing, or could it mean something more serious like a head Gasket failure?
Thanks
Gopi

How long have you owned the car? If you are not the original owner it might be residue from a radiator sealer that was added at some point. If you flush it and you flush out the old radiator sealant which might be coming loose, the radiator might leak. I recomend a flushing with simple flushing solutions available at most parts stores. I would then have fresh 50/50 coolant ready to go in. I would fill it half way then add a bottle of Barr's radiator sealant and finsh filling the radiator. Run the engine to operating temp and take it for a 10 minute drive. When it cools down after shutting it off, check the fluid level again and top off as needed. Run the car an additional 30 minutes and check when cool. All the air should be out of the system then. Have Fun!

:nono: No sealer! :nono:

If its broke fix it, don't clog up everything because of the goop. Pressure test it, flush it, replace radiator cap, pressure test it again and go from there.

The Mythconception of Barr's Sealant. Though removing the radiator and having it repaired or replaced if needed is always preferred, if the car is a 21year old everyday beater and one does not have the time, knowledge or money to do it right, one bottle of Barr's is a safe alternative. I have used this in cars, cranes, excavators, dozers, Bobcats, tractors and generators over the years without incident to water pumps or heater cores. But I agree if the vehicle was my "Baby" and the time and money were available it should be done right. Barr's, though it does work is only a stop gap.

The Mythconception of Barr's Sealant. Though removing the radiator and having it repaired or replaced if needed is always preferred, if the car is a 21year old everyday beater and one does not have the time, knowledge or money to do it right, one bottle of Barr's is a safe alternative. I have used this in cars, cranes, excavators, dozers, Bobcats, tractors and generators over the years without incident to water pumps or heater cores. But I agree if the vehicle was my "Baby" and the time and money were available it should be done right. Barr's, though it does work is only a stop gap.

I can see where it has worked for you and can respect experience, I also have personal experience with Barr's. Not good. I am curious what the 'Mythconception' is.

With respect the "mythconception" or myth and or misconception is that Barr's only wreaks havoc on coolant systems by clogging the core of the radiator and heater thereby creating less coolant flow and causing an overheat situation. It can if your system is not properly flushed or is so old that it has started to corrode internally so the Barr's only exaserbates the problem. It's unfortunate that you had bad luck with it. I do agree with you on the "Right" way.Since the originator has not responded I can only say we are both right according to our unique experiences.

Thanks a lot for the advice. I think I will replace the radiator and hoses and cap. These repairs are very cheap in Saudi Arabia when compared to the US or Europe. With the extremely high temperatures here ( 50 C ) sometimes , it will be most unfortunate to have the radiator spring a leak 50 miles from nowhere.:smile:

You may want to change the coolant every 18 months...it's getting real workout there in the heat. I always changed mine every 18 months and never had a corrosion or radiator problem. (Sold my 1986 Merc a couple years ago)