My '85 C4 restoration
- Thread starter Skvitt
- Start date
- Thread starter
- #42
Hi Serge. Im Vikingtrad3r. Im in YYC. Its -40 and dont want to leave my house! Im excited for your project. Love that color.
So it sounds like u r making headway on returning the cooling system to factory operation. I can assure you factory operation will be perfectly fine.
****Can u verify that you just said, the wire from the single pin, horn shaped connector (its the same connector as a knock sensor connector) was run rearwar from 1-3 head location, then turned to passenger side (behind distributor?) and connected in with the harness at that point?***
So it sounds like u r making headway on returning the cooling system to factory operation. I can assure you factory operation will be perfectly fine.
****Can u verify that you just said, the wire from the single pin, horn shaped connector (its the same connector as a knock sensor connector) was run rearwar from 1-3 head location, then turned to passenger side (behind distributor?) and connected in with the harness at that point?***
Serge, couple comments about C4 cooling system operation.
Its EXTREMELY common to have them all butchered up good.
Reason is, that GM switched locations and setups around mjltiple times in the early cars. Before the time of the interwebz, it was HARD to sort through all this. And so owners would give up, bypass relays, run custom buttons, and generally make a mess out of a perfectly good system.
However, the C4 is a very tight package under the hood. If the cooling systems were not maintained (most were not. these were getting real old and unpopular in the mid 2000’s) the cars WILL overheat.
Numerous overheat causes. Ive had it happen to that 4+3 ironhead (your 85 is ironhead too).
- old fan motor begins to draw too much current, and the fuseable link burns on its way to the relay.
- fan motor dies
- relay gets seized gummed up or burnt up if someone previously removed the fuseable link.
- leaves. needles. plastic bags. nests. grass. gets lodged between the ac condenser and the radiator. grab a flashlight and look in there. get in there real good and see what material lies sandwiched inside the shroud.
- missing front air dam. ive seen this lead to high temps but not to overheats.
- plugged/clogged catalytic converter. (in this case, u will have sky high oil temps as well)
- ive never seen the ecu pinout not working but its possible.
-common to have a faulty rad cap. Even more common to have a rotted/unsealed overflow hose. This allows coolant to escape but not to return due to a vac leak. before you know it, coolant in the rad is low and u boil over. Vac leaks also common at waterpump gasket leaks, and intake manifold gasket leaks. these lead to issues that result in an overheat eventually.
-common to overheat due to needed a few burp/vent cycles after a drain/fill.
- weak water pump or plugged rad (nothing specific to c4 there).
- and ofcourse a blown 7 or 8 head gasket. my 85 had this. that was an adventure.
The factory fan does not even come on until 108d Celsius. that in and of itself gives many the heebie jeebies and causes all these manual switches to be installed to override the factory system. even though 108c is perfectly fine on a c4.
There a quick list of things to check as u r getting to know ur new summer ride.
Its EXTREMELY common to have them all butchered up good.
Reason is, that GM switched locations and setups around mjltiple times in the early cars. Before the time of the interwebz, it was HARD to sort through all this. And so owners would give up, bypass relays, run custom buttons, and generally make a mess out of a perfectly good system.
However, the C4 is a very tight package under the hood. If the cooling systems were not maintained (most were not. these were getting real old and unpopular in the mid 2000’s) the cars WILL overheat.
Numerous overheat causes. Ive had it happen to that 4+3 ironhead (your 85 is ironhead too).
- old fan motor begins to draw too much current, and the fuseable link burns on its way to the relay.
- fan motor dies
- relay gets seized gummed up or burnt up if someone previously removed the fuseable link.
- leaves. needles. plastic bags. nests. grass. gets lodged between the ac condenser and the radiator. grab a flashlight and look in there. get in there real good and see what material lies sandwiched inside the shroud.
- missing front air dam. ive seen this lead to high temps but not to overheats.
- plugged/clogged catalytic converter. (in this case, u will have sky high oil temps as well)
- ive never seen the ecu pinout not working but its possible.
-common to have a faulty rad cap. Even more common to have a rotted/unsealed overflow hose. This allows coolant to escape but not to return due to a vac leak. before you know it, coolant in the rad is low and u boil over. Vac leaks also common at waterpump gasket leaks, and intake manifold gasket leaks. these lead to issues that result in an overheat eventually.
-common to overheat due to needed a few burp/vent cycles after a drain/fill.
- weak water pump or plugged rad (nothing specific to c4 there).
- and ofcourse a blown 7 or 8 head gasket. my 85 had this. that was an adventure.
The factory fan does not even come on until 108d Celsius. that in and of itself gives many the heebie jeebies and causes all these manual switches to be installed to override the factory system. even though 108c is perfectly fine on a c4.
There a quick list of things to check as u r getting to know ur new summer ride.
you *could* reposition the sensors so they are on the correct side. Should be a female blade plug off the harness on driverside that plugs onto the blade plug that is supposed to be on the ds btwn 1-3. (which is right now on the ps btwn 6-8).
then if u replace that relay.....may work.
check that u r getting 12v in from that hub post behind battery. when mine died, it was the fuseable link there that fried (due to a crappy old motor that was drawing to many amps). i cut the burnt part out and resoldered it.
One BIG thing to check if you havnt.
Short A and B in the aldl using a paperclip or something like that in the picture. The FAN SHOULD TURN ON AND RUN.
if the fan doesnt turn on, need to diagnose this.
- Thread starter
- #46
Yes, the wire was running from this sensor located on driver side to this wire on the passenger side. Furthermore, I went out , hooked up the battery, installed new fan relay and tested the circuit. Firstly fan relay fuse was blown. Secondly when I ground that green wire, fan comes on. Which agrees with the diagram. So I will reposition sensors.
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good job. and welcome to the wonderful world of c4 corvettes. where the past 20 ish years of ownership have been by broke bubbas who never fixed anything properly.
You're very brave and I hope you're very patient!
Buy yourself a bunch of Rubbermaid containers and zip lock bags to keep track of your parts removal. Take some good pictures and label stuff as well. In a few months you"ll be looking at a box and have no clue. I've done several restorations and these things will help you. Good luck with the project !