Gunged thermostat!

[Danbuoy1]

Helping out a friend who has 1974 1300xl escort, had car rebuilt couple years back, recently said car overheated and asked my advice (as I have old Triumph and Mondy). Rebuilder has moved away and not local, not easy to get car to them.

Coolant flowed out of overflow as car warmed up.

Temp gauge didnt register, put new temp sensor in, gauge registered and coolant flowed out before it indicated "normal" but top hose/rad was cold. Took stat cover off and was staggered to find it was coated in a black gunge. It cleaned in water and lots of black bits and sediment in basin, tested and ok. Put back and this time all was much happier, maybe the gunge was shielding the stat? However (apart from recommending a  complete flush) any thoughts? Heard problems mixing antifreeze types altho guy says he hasn't added any, not sure myself...

Cheers

SD

[unofix]

A 1974 Escort would have used the old Ford BLUE coolant which I understand is now no longer available. You can use the Ford RED coolant which is the type used in all Ford cars now BUT the two types do not mix. If changing from the old blue coolant to the new red then the system needs a good flush first.

[Danbuoy1]

Many thanks for quick reply - confess I get confused by these colours - I use blue in my Triumph but red in our Ford's, the escort owner has a Cmax, just wondering if he used that antifreeze to top up escort and caused a problem. In my (50+ years) never seen a thermostat covered in what looks like black jelly!

 

[Ian Keys]

Hi it sounds to me like others are saying it could be 2 different types of antifreeze that arent compatable having a chemical reaction and causing a blockage. Another possibility is someone has tried to flush the cooling system and heater matrix inperticular which hasnt worked as well as they thought. I had this problem with my Audi 80 coupe when trying to get more heat out of the heater. Maybe they have tried a chemical flush to try and unclog the heater matrix and it was too aggressive and melted the plastic parts in the heater matrix which has turned into a gunge and caused a blockage. I remember someone using something like a sink and drain chemical which done this to a heater matrix. Its just a thought but it does sound very similar.  I hope u find the problem. Good luck from Ian!