I’ve got an EB II i6 4L, rebuilt a good few thousand k’s ago. When it was rebuilt the radiator was changed with a new one; not reco, new, I brought it myself. The cars also had a thermo fan conversion for over a year now. About 2 weeks ago I started having issues with the heater cutting out and temp rising while sitting at lights on my way home from the city. The fans would cut in, but it was not until I would start driving that hot air would start to come out of the vents gain, and no it wasn’t a vacuum issue. I replaced the thermostat and the heater issue stoped, but instead the car started to get much hotter before the thermostat would open and drop in temp. As an example I have the high series dash in my car, and normally the car would sit on the ‘N’ in relation to the word ‘Normal’ written within the gauges normal operating range, and get about half way up before opening the thermostat, but it started to sit a little higher and would get all the way up to the ‘L’ now before you would suddenly see it drop. I decided to replace the thermostat again with a different brand. The one I now have also has a predrilled hole in it with a small valve that appears to allow some coolant flow while the thermostat is shut. This one however is no better than the last. On top of doing opening late and running much hotter, now about half way, it is also fluctuating while I drive, even at 100kmh along the freeway it will still be going up and down in temp. Anyone with some past experience able to shed some light on this issue? I went through the cooling system air purge procedure last night but today on the way to work it was still doing the same thing.
Another note, after reading a few posts on the forums, no, I don’t believe the performance has dropped off either. Fluid level and oil levels are fine, using coolant with correct mix for the engine, and running high quality oil, same stuff I’ve been using since the rebuild, changed at regular intervals. I have not fully investigated the issue yet, but I’m after anyone’s experiences with this so I have something to go by when I have a look again tonight.
Ok, thought occurred to me on the way home from work. The temp fluctuation only seems to happen when the car is moving, ie. the revs are up. This indicates to me that it could be a problem with the surge tank cap as higher revs mean more pressure in the cooling system. When I got home I noticed the bottom of the overflow hose and surrounding area was rather wet, and shortly after noticed a puddle of water that had leaked from the overflow. The surge tank is not overfilled, so it really should not be leaking. Will replace this and see what happens.
What about the bottom radiator hose? Is it collapsing under the effect of suction while the car is moving at speed? It should have a sprial spring inside it, almost the full length of the hose. Check it out and replace the hose if it is spongy or soft.
Ye, good point but the bottom radiator hose is fine, replaced with the engine and the spring is in place. Feels very solid, and not because of pressure behind it.
Replaced the surge tank cap, and the cars running a little cooler again but still fluctuating. I guess it acts like I'm driving around with a restriction in front of the radiator; it gets up in temperature while driving but doesn’t seem to be able to lose the heat until the fans come on and force air through the radiator, where normally the air being pushed through the radiator by driving is more than sufficient, and its not very hot here at all at the moment.
I don't know a huge amount about the cooling system in our cars, but what I DO know is that my car quite often lies to me. ie my water light comes on, and the surge tank is full or the oil gauge says the oil pressure is off the chart and its not. Considering that this is a problem that has occured suddenly I would consider checking the wiring to the water temp sensor, and the sensor itself. Perhaps with a thermocouple or a trusted water temperature gauge, you may find that your water temp is perfectly fine
Ok found the issue. Actually I’m ashamed I didn't pick up on this earlier. When the rebuild was done I never thought to specify that they use the thermostat housing to head ‘metal’ gasket available through Ford as I have done on all my E series, so they offcourse used the standard paper gasket. Consequentially it had developed a leak on the underside of the thermostat housing. Simple fix replaced the gasket with the metal one from Ford, a bit of good sealant and its now running fine. I do think that my problem was twofold in that the surge tank cap was stuffed, big difference between the condition of the rubber and spring in the old one to the new one. But once I replaced that and it built up more pressure in the system it found the next week spot, the gasket. I’ve had it out for a long drive, whereas it normally only takes less that 15 minutes for the issue to crap up, instead it now sits on the N, occasionally getting to the O and then dropping back down, and the thermos never come on. Only crept up a bit once at a long set of lights and it went back down once the thermostat opened up again. Flushing the system now and going for some Nulon coolant as opposed to the factory stuff they used in the rebuild. But all in all its running like my engine used to again.
I will say this, next time you need to change the thermostat housing to head gasket on your E series, make sure you get the metal one available through Ford (no one else seems to carry them) Part number from ford is AU 8255 A.
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