Hi Folks,

I'm in the process of replacing the engine valley heater hoses and thermostat tower (while troubleshooting an engine running hot) - because I don't have the specific maintenance records for this car, and I figured on doing preventative maintenance while I have stuff apart.

My question is this: is this hard white coating on the inside of the plastic cooling system parts evidence of stop leak being used on this cooling system? I had read of this on the board, and I certainly haven't added any myself. Plus by the look of it - the lower radiator hose has been replaced, and to all appearance (mismatched bolts on the pulley) the water pump and thermostat have been previously replaced - but the radiator certainly *looks* factory.

People have mentioned testing flow on the radiator by forcing water into the inlet and seeing what the flow is out the output side -but that sounds ... a bit subjective/

I've added a picture below of the coating on the front coolant manifold.





Similar coatings are found on the internal passages of the thermostat tower - but not inside the apparently replaced main radiator hoses.

Input is welcome
White coating on front coolant manifold interior

 

Does the car live in an area of "hard water" as it looks like hard mineral deposits.....

 

It has for at least several years that I know of. Before that it lived on Long Island NY

 

I have encountered the coating in the past on my XJ-8. Most likely it is not the result of someone using a radiator sealant. More likely they topped up the coolant with something not compatible with what was inside already.

If you have it down and drained I would fill the system with water only, bring it up to temperature with a brisk drive and drain it again. Then refill with the coolant of your choice and make sure any new topping off is with the same type.

E.G. Orange (OAT) coolant or Green (non OAT) coolant.

 

This is why you should always mix coolant with distilled water, not tap water.

 

This is exactly what I did after encountering the engine getting hot enough to run both fans continuously. During a test drive the engine worked its way up as high as 226 on the odb2 coolant temp.

My lack of results led me to tear down to the valley heater hoses to check and replace original components - (thermostat, housing, waterpump, valley hoses) which I am now doing, even though I see no signs of any problems/ leaks with the originals, and despite signs that the waterpump and thermostat are replacements

appreciate the input and confirmation of my thinking

I am starting to suspect a .marginal radiator in this scenario ...

 

jimborino,

i am new to the site and just read this...how did it all turn out ? any new info/ thoughts to share ?

many thx,

max

 

When I bought my '98 xk8 it had a small coolant leak I replaced the hose then another would go. I ended up replacing all hoses, thermostat and bought the best radiator that I could. Before installing all new parts I flushed the cooling system 3 times. Since then not a problem. I've owned my xk8 for about 2-1/2 years. I recently got a very low mileage engine, going through the entire new engine with my buddy who is a certified master mechanic, mostly on Fords. We're almost ready to drop the new engine in. Tranny rebuilt about 500 miles ago. The one coolant hose that convinced me to redo entire cooling system was the transmission cooling line. Remember that on both sides of your radiator is plastic and living in a desert climate like Arizona plastic breaks down faster than most other places. With the kind of buildup your showing I would definitely flush your cooling system then replace all hoses. Use a scope to look down inside the radiator or any other area that you can. For me, once the new engine is put in with everything else that I've done, all parts replaced with latest series so she should be better than the day she came from the dealer. Car has only lived in the desert.