So a lot of that went straight over my head. I definitely appreciate the assistance but much of what you mentioned confused me.

Why do you suspect that the sensor would be destroyed in an attempt to remove it? are they frail?

Also, with the NTP plug, I didn't understand a bit of that.

Keen to learn about all that though.

 

NPT National Pipe Thread - a taper thread that will pull tight and therefore make a fluid-tight seal.

 

If your 84 car has the original knock sensor, then it is roughly 32 years old. The chances that the original can be removed without causing some sort of damage to it, is very slim. WVZR-1 is suggesting you get a replacement before you attempt the removal as a backup. If you successfully can remove the sensor, then just return the new unused one. If you damage the original one, then you already have a replacement you can install after your block flush.

 

he was just telling you to make a hose that screws in the knock holes to flush. and the knock is over 30 years old best to replace.

 

So with that said, I should just be able to get a 1/4-18 NTP plug like WVZR suggested as a replacement for the corresponding part already on the engine /and/ a new knock sensor just in case?

I'm pretty sure I have that straight now, cheers.

 

So I've done a bit more research on this whole knock sensor thing, and it seems horribly complex. Taking it out without busting it seems the easy part, then putting it back in has to be done with finesse and tightened to a specific strength?

Read on another post that some guy had to do a ton of work to get his 90 back in working order because he muffed the KS reinstallation. A tad daunting.

 

The only potential complication is due to possible rust in the threads. Otherwise, this is an easy operation. Yes, only one KS in the '84. In my area, electrical parts are not returnable to the parts store. This is a pretty rugged device, so I'd say the risk of damage to the KS is small.
When you install the KS, use some thread sealing compound, since the KS goes into the water jacket. Do NOT use teflon tape, since a good electrical ground ("earth" in your territory, I believe) is required.

The KS is covered in the '84 FSM (Factory Service/Shop Manual) pg. 6E2-90, but the installation torque is not mentioned.

Interesting connector on the KS. Squeeze the sides of the conn. then pull it straight off.

 

It's hard to say why auto parts stores would recommend a "red" coolant Are they referring to a long-life coolant like Dexcool??) other than maybe they make more money on selling that coolant.

The '84 was filled with a 50-50 mix of green ethylene glycol coolant and water from the factory. There's really no reason to go to something else as you could find that different types of coolant do not mix and can cause some big problems. This is the case with the green coolant and Dexcool.

Given the age of the coolant that's in the car, I would recommend using a cooling system cleaner as part of the flush process. There could be all sorts of goop in the system that a simple flush with water may not get completely out. Once the flush is done and the old black coolant is completely gone, it would be a good idea to replace both radiator hoses, the thermostat, and as many of the hoses going to the heater as you can get.

Check for dirt and debris that might be between the fins and tube of the radiator and A/C condenser. C4's are "bottom breathers" in that cooling air comes up from under the nose and passes thru those items. If airflow gets blocked, you could see higher coolant temps and the A/C may not work as well. A garden hose works to get that stuff out. Just aim a stream of water from the fan side of the radiator to get a lot of the stuff cleared. A vacuum cleaner can also work if everything is dry.

 

OP - I considered both the way the original KS is assembled and also your location. The assembly is a crimped affair and I doubt it survives the removal from the block. The NPT plug on the other side is a maybe. I would locate the KS locally maybe before I started the removal so that if I did destroy it I'd be able to put my hands on it easily.

GOOGLE is your friend for an image: GM 10456017

You might consider maybe just using another plug temporarily until you accomplish a satisfactory flush.

I believe the torque mentioned most frequently in the FSM for the KS is 14 lbsft

 

Cheers for all this help guys! It must be annoying for you all to explain this all repeatedly but I do appreciate it.

Going to attempt a flush (water incl. flush liquid) and I'll report back here.

If nothing else this is just going to be a temporary fix until I can make time to do a full service later on when I know a bit more of what I'm doing.

Cheers!

 

ill get u a pic. not sure why people think u r going to wreck your ks ive had mine on and off 10 times. (dont ask). u will need a deep socket though. ill show u pic of that too.

and if u want to tinker/wrench on your car, u will need a torque wrench so u know u u r tightening things the right amount. u can save like 75cents on the dollar by buying your tools on a site like craigslist or kijiji. (meet at a public location).

 

I was wrong about a deep socket. it does not appear that you need one, although I always use my deep socket 7 eights not sure why. Here are pictures of the knock sensor and then you will also see pictures of the drains that get screwed into the knock sensor whole witches others have said are one quarter size npt , Or national pipe thread, and then you stick a bunch of various adapters to make it into a garden hose size you can do it at Home Depot the last little bit for the garden hose size go over to the brass fitting section where the garden hoses are or just ask around and you'll get everything you need. The 45° bend works nicely because the block itself is at 45° so your drain is pointing straight down you put your garden hose onto it. just make sure you have a way to plug your hose that could be as simple as a pair of vise grips. run the car with a flush water in it and then drain wait for the block to cool down and then refill it with hose water and then run it again and drain it again repeat repeat repeat. If you have the thermostat out of the car it goes much faster. But if you don't have your thermostat out of the car you have to wait for the car to heat up to open the thermostat each time which for me was 180° and then you got a let it run for a while so that it actually circulate somewhat before you turn it off and drain. Some people have drained the car partially and then actually filled the car up while it's running but the danger there is if you have a really hot block and you pumping cold tapwater do you run the risk of warping are cracking a little bit somewhere.







1985 knock sensor on passenger side of block. access from under car.





7/8





my first gen ks drain used a plastic (the black one) 1/4 nipple. it actually didnt melt but switched to steel anyway.

 

Alright lads I said I'd keep you updated so here's the first batch of sh*t to pour out of my radiator.

Ran two or three flushes of distilled water/flush liquid and got this (mostly all over my driveway, thanks GM for such a stupidly placed drain plug)

It's currently a lot clearer passing through the system now, but still murky. Currently only running distilled water as I only make short drives for now, but the car is already staying far cooler through all phases of use.

Will be flushing some more tomorrow before using my coolant, wouldn't want to waste it! Trying to get max gunk out as possible.



EDIT: it's just filthy water, no traces of oil so I'm not concerned about any head gasket issues like people I've spoken to have suggested.

 

looks like my 85 which had "irontite"put in it. when I pulled my heads off to do a head gasket job I had irontite built up all of the place. The way it works is it areas of depressurization it flocculates and basically forms a gasket it actually works pretty well but it leaves your cioolant looking like a mahogany color that you could stain the deck with

 

do not. not not use anything other than green 50/50 mix. and while u r doing your flush, get a 15$ bottle of flush cleaner, i used the predtone version and it was great. leave it in for 3 days driving each day as a daily driver each day. just follow instructions on bottle.

now that u have flushed usinf water, u will be flabbergasted with the anount that the chemical douche pulls out.

 

keep flushing and driveing till clean no worries off freezing there. not sure about the flush over there here the EPA has reduced it to cool-aid. I would use the hose to flush it and save the distiled water for the final flush and for the fill. I add a bottle of water-wetter in the fill.

 

i agree about the water! dont waste the distilled.

i also ran the car for a day with vinegar. that got rid of alot of rust. but the prestone flush mix was more powerful than the vinegar. next time on my other c4 im going to skip the vinegar and go straight to water flush twice then do prestone flush left in for 3 or 4 days.

take more pics OP! we love pics!

 

when was the last time you used the prestone flush? I just did it and found out about the EPA and the guy gave me a bottle of the old stuff out the back door. new him for over 20 years. the bottle looks the same but you might as well **** in it.

 

not too sure about that. i live in canada.

 

The '84 has one knock sensor and it is hidden behind a cover that is held by an oil pan stud/bolt. It is in what used to be a drain plug hole in previous small blocks. It also uses one of those "mushroom plug" connectors that get brittle from heat and time so be careful removing it.

Very nice early C4, enjoy.