C4 1987 Overheating.

[Vettech]

Over the past three years I've rebuilt & corrected the cooling layout.
This started after the heater matrix blew up, but strangely I managed to get from Brookes Rd to Cecil Hills, whilst I could smell the antifreeze, there was hardly any fluid on the pass floor, upon starting repair, it became obviouse why. All hoses, pumps, fittings, oil coolers were corroded chockabloc full of rust & corrosion, not to mention kinked hoses and dubious routing.

All the above along with a rebuilt power steering pump, now see's the car ready to go. Switch on, start up..... ummm a bit rough (have not fitted new leads yet), a couple of goes around the block (~less than 50kph), and the temp was getting up to 114 C° and on the way to boiling when the Aux Coolant fan came on - in fact I dont think i'd ever heard the Aux fan run. Umm get the books out and refresh my understanding of C4 cooling. The Cooling Fan (CF) comes on when car starts, runs contiuous up till the car reaches ~65kph at which time it switches off unless other extremes cause the engine temp to rise out of the ordinary, if the temp goes up further the Aux fan comes on.

The fault was either, the CF, it's relay, ECM control, general wiring or power supply. Found the relay and with the help of my trusty helper we asertained the relay was Ok, ECM control OK, once unplugged we slipped a 12v feed onto the CF run wire, and on she came, ergo the CF is OK. Now out came the metre's etc, sure enough no juice from Fusible Link "D" but it looked Ok, no burning, blackning or anything untill a close look, whilst the fusible link looked perfect untill you pulled on one end and the red/orange cover parted and wollah there is no longer a wire inside the sheath - magic.

[Vettech]

Pic of the Fusible Links, D has parted, whilst E is ok and runs the Aux fan, both are sealed within a plastic barrel, which has a marking moulded into it - "20" - I'd guess here it means 20 amps capacity. Move pic sideways the see all.

[Vettech]

Now I've looked on line here and US.

These types of Fusible Link setups do not seem to be available, of course I can bodgy something up, but alas forever the perfectionist, I'd really like an original (New not 2nd hand) replacement.

Has anyone out there seen, bought, know of where I can get a replacement.

Many thanks.

[Vettech]

A big thanks to those two members who sent info about two suppliers of "wire type setups".

I know I waffled on to start with, but now I'm pretty certain, that this whole Overheating saga is more or less down to the failure of the main coolant fan to run. The Temp/press went well up causing old age & corrosion in the heater matrix to fail.
The fusible link was a red herring - sorry Orange herring, in that it was very near to parting ways, when a big pair of gumby hands helped it to break, this area of the engine bay had A/C, heating & coolant hoses not to mention exhaust and wiring moved, heaved upon and wrenched about in every direction in an attempt to fit the a new heater matrix and resolve water etc directions of flow etc. Why do I say this, because I've by-passed the fusible link, manual operation of the relay/fan is OK, the relay coil 12v is OK, but the earth coming from the ECM (ie, the fan controll lead) has nought on it - ergo: the ECM is not sending a signal out, hopefully its the wire between relay and ECM. Either way this is a PITA.

[sirfixalot]

not unusual to have more than one fault on a circuit

[Vettech]

Pic of the three fusible links (E, D & H)

The red lead at lower left is the power into the split. The upper lead is fusible link "H".

The two orange wires are "D & E" (move pic across) these WERE both sealed in the 20 slug, one had parted and whilst getting this out the other link also broke away. Which means that in normal wear & tear, this second link which feeds the "Aux Coolant Fan" would have broken and because we never see or hear the Aux fan run, we therefore would be none the wiser untill the catastrophic end.

So now to knock up an identical replacement. Oh! The 20 slug to the best of my knowledge means 20 gauge not 20 amps as I first thought.

[Vettech]

OK!  Xmas is over, back to those fuzes.
As mentioned I rec'd several lengths of 20g fusible link wire.
This has now been refashioned into the pic below.

The two new links are for the D and E feeds to the Main Fan & Aux Fan respectively (rad coolant fans)
The other black plug is for the H feed covering Fuel pump, ECM, Mass burn off etc etc.
The pic shows the barrel crimp in the centre, two grey 20g (D&E) feeds, the red H feed and the green supply feed in.
The black shrinky dink not yet in place.

[Vettech]

This pic is the finished product.

Now to refit and hopefully all will go well.

[MY081]

VERY NICE WORK UNCLE DOUG!!!! RAY.

[sirfixalot]

I had one defective on my c4 I just fitted a weatherproof fuse holder and blade fuse from Jaycar from memory it was for abs pump. Good work Doug for persevering to get it right

[Vettech]

I hear you Geoff, but its location is a bad one, only inches away from the manifolds, even if they do have heat shields over them - it gets very hot and those plastic holders you mention would not fair well.

But all is working well, fan wise, now to fix the hairy dog it's running like.