temperature spiking

[Doug-n]

Apologies if this is a common question - I could'nt find any entries in the search.

Got a 1999 Eplorer (uk) model approx 115,000 miles, 4.0l sohv, converted to run on LPG, recently temp has started to spike at start up.

Temp climbs as normal for about 5 miles, heating normal.

heating then goes stone cold and engine temp climbs off the guage, stays there for about 0.5 miles then drops to normal.

Engine temp stays normal but heating remains cold for about another 3 miles, then temp spikes off the guage again.

After another 1 mile engine temp drops to normal and hot air returns to heating system - vehicle then runs normally.

This is consistent 95% of the time on startup (either hot or cold).

Local Ford dealer has change thermostat and water pump, back flushed heating and cooling system to no avail.

has any one any suggestion where to look next??

tia
doug-n

 

[TPLYNCH]

Did they try replacing the radiator hoses? If one of them is weak, it could collapse on itself, restricting coolant flow. Are you sure they "Burped" all the air out of the system? Also, do you have the OHV or the SOHC engine?

Another person on the board had their thermostat break apart when they removed it and had to fish pieces out of the engine. When they replaced yours, they got all of the old one out?