hpracing

89s4 been running hot in this cool weather creeping past the third white line.pulled radiator did a garden hose flush got a half cup full of junk and settlement .radiator is at shop going to be cleaned rott clean pull tanks,are the o-rings available and any tips on flushing block to get the junk out of the block.

Tom in Austin

Check with Roger at 928srus in Dallas for the o-rings. My car's cooling system has been plagued with rusty crap as long as I've had it ... not sure where it's coming from since I think the only ferrous metal in the system is the Y-pipe on the R inner fender and the reinforcing inserts in the coolant bottle.

I've drained and flushed my radiator (a couple of times) but haven't pulled the freeze plugs to completely flush out the block maybe that's why I keep seeing the junk in there ?

Mrmerlin

I wouldnt have them remove Both the tanks to clean out the rad,
it might be last time you see your radiator.

at the most have them just remove the right tank and replace it leave the left tank alone.
NOTE Roger sells new side tanks and O rings
Rust may also come from a metal heater control valve or the water pump impeller or the Y tube.
Tom pull the plugs on the block getting out all the junk is whats needed.

For the running hot you should inspect the thermostat and its rear seal.
Also get a block tester and see if you have any hydrocarbons in your coolant NAPA sells the tester if you do have hydrocarbons then its either a leaking headgasket or cracked head or block

Tom in Austin

Stan, are you referring to the difficulty of opening and re-closing the aluminum tabs that capture the side tanks when you suggest only doing one side? Would you suggest always going with a new tank as a wise preventative move?

dprantl

There is also a metal pipe under the coolant expansion tank that likes to rust.

Dan
'91 928GT S/C 475hp/460lb.ft

hpracing

radiator shop called me, said they did a flow test,they said at least 40% of the radiator is plugged up,thats the reason for running hot and not cooling properly,got some new o-rings coming, next week i will let you guys no what the temp reads.

Mrmerlin

Tom and HP, If you have them remove a tank make sure to put a new tank on esp the right side tank this is the one that fails and they all will fail.

The left side not so much but if its off then put on new it would suck to have your fresh cleaned rad start leaking from a fractured end tank

NOTE on the right tank there is a slotted flow control in the inlet if your new tank doesnt have this then it has to be transferred also get the O rings for the inner trans or oil coolers,
when you order the other parts

David L. Lutz

Here is the pipe, had to replace mine it had rusted thru. IIRC this part is expensive over 200.

joejoe

When I did my '84 944 w/p I used CLR solution in radiator when it was out. This car never ran hot and nothing much came from tank after CLR flush. Car still runs at first line when hot (in summer) With a/c on it creeps up to near middle.

dr bob

Chem solutions may be the only way to get the last bit of deposits from inside the tubes. The radiator tubes themselves have 'turbulators' inside, essentially spiral fluting on the inside walls of the tubes that upsets the normally-laminar flow. The idea i to get the coolant to move around so that more of it gets to contact the tube wall. There's also a little extra surface area available on the coolant side. It's a great way to get max capacity from a liquid exchanger, but they are hard to get clean if you have a lot of precipitate or minerals in your coolant plating out on the tube walls. The deposits seem to plate out in the voids in between the flutes, eventually making the inner walls smooth. The mineral deposit layer is a pretty good insulator too. So you get some flow restriction, less heat transfer, and there's no good way to 'rod' the tubes out and actually get them clean.

All that said, most cleaning chems, including CLR, risk damage to the aluminum tubes as they work to soften the mineral deposits. The tubes themselves are pretty stout, but there's a risk that some of the chems will hide out in areas around the tank junctions with the core. These are 'dead zones' where a little bit of corrosion over time will risk leakage around the edges of the o-rings. If your tanks are off anyway for mechanical cleaning, no worries since you'll be able to thoroughly rinse and neutralize the chems before reassembly.

All that said, my original radiator is starting to show signs of deterioration in flow and heat transfer. 100º+ days, it doesn't like to go over 80mph or so without getting the needle up past the third line. A few weeks ago I decided to disable the flap motor with flaps open, and that showed that the thermostatically-regulated temp is somewhere just a needle-width right of the second line. Running downhill for a bit in 50º temps pushed the needle well left of the second line after just a mile of downhill at 70 with the fuel cut off. Maybe not so good that it gets so cold with the flaps always open, so I may go back after the flap operation again with a little mod to the sensor circuit in the bottom of the radiator. Need to separate the ranges so the flaps open a bit colder than where the fans start running, and that will take some sleuthing in the circuitry inside the controller I suspect. I have an extra one for guinea-pig purposes, and will report results.

hpracing

my radiator ended up being junk,bottum side was coroded enough there was no saving it, bought a new all aluminum two core set up,test drove 60 miles with ac running,it didnt even come close to the third white line,maybe two lines past dead center of gauge.no more running hot,awsome.

Mrmerlin

cool glad you got it fixed