Help! the diary of a lemon

[LT4man]

Back flushing is when you disconnect one heater hose and run water (usually from a garden hose) through the system the opposite direction of the normal coolant flow. The other heater hose is directed into a bucket. This will jog loose any particles of rust and/or corrosion. One would be amazed at the amount of junk which ends up in the bucket.

Backflushing is usually very effective in taking clogs out of heater cores. Backflushing a radiator is usually a waste of time.

AFTER BACKFLUSHING YOUR HEATER CORE, DON'T FORGET TO SAVE THE !

 

[RocketSled]

That's what I figured, but wasn't sure.

 

[tmkassin]

If it occurs to you, ask 'em what back-flushing means. Does it mean they blow out the INSIDE of the radiator for corrosion, or do they blow out the OUTSIDE of the radiator removing debris picked up from driving on the road.

I've always wondered and never bothered to ask.

OK The FSM says there are many possibilities.
Belt tension too low.
Timing retarded
damaged water pump
Thermostat stuck closed
There are some others but these seem to be the the most likely to match your symptoms. As far as the sending unit, it decreases resistance as the temp goes up. If your needle is pegging I would suspect a possible grounding issue or a bad sending unit. I can't find anywhere that tells the correct ohm reading in my FSM but it is for a 1992 anyway and might be different. Good luck

 

[fumesniff]

100 bucks to get a couple leaves out

OK The FSM says there are many possibilities.
Belt tension too low.
Timing retarded
damaged water pump
Thermostat stuck closed
There are some others but these seem to be the the most likely to match your symptoms. As far as the sending unit, it decreases resistance as the temp goes up. If your needle is pegging I would suspect a possible grounding issue or a bad sending unit. I can't find anywhere that tells the correct ohm reading in my FSM but it is for a 1992 anyway and might be different. Good luck

well everyone, today i dropped it off to have the radiator pulled and cleaned... there were a few leaves in there, but other than that it was okay. that didn't fix the problem. made sure the pump, fan, and stat were working again.. and still same problem.
tomorrow i'm going in and replacing the sending unit.(is the sending unit to the gauge right there on the driver's side of the block? or is that the sensor that tells the chip whats up?) anybody got a price for that? dam near broke... i suppose if that doesn't work i'll have the ignition timing looked at.

 

[tmkassin]

well everyone, today i dropped it off to have the radiator pulled and cleaned... there were a few leaves in there, but other than that it was okay. that didn't fix the problem. made sure the pump, fan, and stat were working again.. and still same problem.
tomorrow i'm going in and replacing the sending unit.(is the sending unit to the gauge right there on the driver's side of the block? or is that the sensor that tells the chip whats up?) anybody got a price for that? dam near broke... i suppose if that doesn't work i'll have the ignition timing looked at.

I just thought of something. Is it possible that your thermostat is installed backwards? That might be forcing it closed at higher RPM's. Sounds wierd but might be worth look into.

 

[air1jpg]

here's the deal. i let it idle for ten mins and the fluid temp was still L0. then i started cruzn real light thru the neighborhood. stop go stop go.. all around 20-25 mph. it would heat up pretty fast but stay around 200. but as soon as i would drive with a little rpm (17-20) it would heat up real fast and steadily rise until i slowed down again. actually got up to 250-260 degrees just driving how i would normally drive... with a little bit of rpms. but still around 30 mph.

if i were to do a burnout it would peg i'm sure. on the highway it can peg at 299 within a minute.

also worth noting, when i went out to check how it was doing at idle.. it still said L0 but the fan was on. thought the fan didn't come on til 230?

I would think a temp of 299 would cook your engine to the point of locking up. I think your sending unit needs to be replaced.

 

[minifridge1138]

Well I'm a little conflicted on this one.

It is starting to sound like a bad sending unit.
I know of 2 ways to test:
1) pull the sensor out of the block and put in a buck of hot water and see how the gauge reacts. If the water is 200 degrees (be careful you don't burn yourself) that is about operating temperature, so you can see where the gauge points.
2) buy an ifra-red thermometer. The are the hand held devices that you point at something and it tells you the temp. They are about $75 at Sears. Get the engine warm up and then point the gun at the thermostat housing.

It could still be the radiator.
When I bought my '82 the radiator had been "fixed" with a can of sealant. It fixed the leak and plugged the radiator solid.
It would overheat if you let it idle too long.
Then I replaced that with a light duty radiator. That was ok at idle, but would run over 240 (I love that the C3 gauge has numbers, not "lo" and "hi") in a normal drive. It would be at 260 at highway speeds.
Then I replaced that radiator with an aluminum one from DeWitt's. Now I can drive up hill at 75+ mph with the AC on when it is 100 degrees, and my temp barely touches 220. I'm not exaggerating.

What you're describing sounds a lot like my early problems: ok at idle, but gets too hot, too quickly.

Are you sure the water pump is working?
A lot of pumps have an aluminum shaft and propeller.
If they corrode, the propeller breaks off from the shaft.
As a result, the belt is only turning the shaft. The spinning shaft can cause enough rotation and flow that the car will "burp" the air out of the system, but not much else.
Unfortunately, the only way I know to test this is to remove the water pump and look at it.

See what the radiator shop finds.
I'd also get the IR thermometer. That's the only way to know if the car is as hot as the gauge indicates.

Craftsman Infrared Thermometer (i'm not endorsing this, it is just an example of what I'm talking about).

Good luck, thank you for the compliment, and I hope you get back on the road soon. Corvettes are fun to look at in the garage, but more fun to drive!!!

 

[fumesniff]

Well I'm a little conflicted on this one.

It is starting to sound like a bad sending unit.
I know of 2 ways to test:
1) pull the sensor out of the block and put in a buck of hot water and see how the gauge reacts. If the water is 200 degrees (be careful you don't burn yourself) that is about operating temperature, so you can see where the gauge points.
2) buy an ifra-red thermometer. The are the hand held devices that you point at something and it tells you the temp. They are about $75 at Sears. Get the engine warm up and then point the gun at the thermostat housing.

It could still be the radiator.
When I bought my '82 the radiator had been "fixed" with a can of sealant. It fixed the leak and plugged the radiator solid.
It would overheat if you let it idle too long.
Then I replaced that with a light duty radiator. That was ok at idle, but would run over 240 (I love that the C3 gauge has numbers, not "lo" and "hi") in a normal drive. It would be at 260 at highway speeds.
Then I replaced that radiator with an aluminum one from DeWitt's. Now I can drive up hill at 75+ mph with the AC on when it is 100 degrees, and my temp barely touches 220. I'm not exaggerating.

What you're describing sounds a lot like my early problems: ok at idle, but gets too hot, too quickly.

Are you sure the water pump is working?
A lot of pumps have an aluminum shaft and propeller.
If they corrode, the propeller breaks off from the shaft.
As a result, the belt is only turning the shaft. The spinning shaft can cause enough rotation and flow that the car will "burp" the air out of the system, but not much else.
Unfortunately, the only way I know to test this is to remove the water pump and look at it.

See what the radiator shop finds.
I'd also get the IR thermometer. That's the only way to know if the car is as hot as the gauge indicates.

Craftsman Infrared Thermometer (i'm not endorsing this, it is just an example of what I'm talking about).

Good luck, thank you for the compliment, and I hope you get back on the road soon. Corvettes are fun to look at in the garage, but more fun to drive!!!

the guy at the shop is bringin in an infrared thremometer today. how hard is it to get to my thermostat.. don't you have to pull the tb's out (crossfire)? can you just point it at the block for a good reading? i'm trying to do this as cheaply as possible. ...

one more question for the masses here before i take it in today... the guy at the shop is pretty adamant that the sensor we need to check is on the left side of the engine... its the socket type one... but the sending unit should be the blade type one on the passenger side someplace right? one of the guys that is working this thing seems about as retarded as my timing and i want to make sure.

just wanted to tell you also... they are tired of messing with this thing, yesterday the owner was sticking a meat thermometer looking thing in the radiator fill cap and bumped the hood support.. the hood fell on his head and he jammed his fingers into the hot water.

i was looking at putting in an aluminum radiator after payday. but on an '84 you have to upgrade the condenser or something to make room for it.

wow.. this is a really long thread. i owe you guys a beer when its all over.

 

[crash]

first question ? how old is the readiator. second question. you said it idles and it is cool. but when you drive it it heats up rapidly. you also stated the coolant fan is running after you started it. is it the secondary fan for the a/c or is the car equipped with only one fan.
an educated guess is your radiator is clogged up. the first thing i would do is confirm the temp gauge is correct. if so replace the radiator.
ive been working on cars for 40 yrs and it sounds like your radiator is stopped up. also do you have a fsm. if not get one and start reading.
rich

 

[fumesniff]

first question ? how old is the readiator. second question. you said it idles and it is cool. but when you drive it it heats up rapidly. you also stated the coolant fan is running after you started it. is it the secondary fan for the a/c or is the car equipped with only one fan.
an educated guess is your radiator is clogged up. the first thing i would do is confirm the temp gauge is correct. if so replace the radiator.
ive been working on cars for 40 yrs and it sounds like your radiator is stopped up. also do you have a fsm. if not get one and start reading.
rich

only one fan, and it does blow when i get it up to temperature. the reason i don't think the radiator is blocked or the stat is stuck closed is because a mechanic the other day said it looked like i had good flow in and out. also when the gauge does spike real fast it cools down almost as fast.
as far as the fsm is concerned i ordered one from a vette parts place a while back and they sent me the wrong book. when i finally got it sent back they returned my cash and said they were out of stock... doesn't matter, i'm not an aspiring mechanic and i wouldn't understand the manual anyway. i know what your gonna say... if you don't know how to read a fsm, you shouldn't have bought a vette. well... when i bought the vette i was lied to, within the seventy miles the engine blew, next the tranny was shot... every single part of this car broke before i had a thousand miles on it. i didn't know the 84 was such a beast, but i think it is a work of art and no matter how many months i have to work without a day off i will get this thing running the way it deserves... book or no book.

 

[gmjunkie]

i guess the way to check the sending unit would be to manually check the temp somehow. it would be pretty hard to test the liquid temp with a liquid thermometer with the cap off... i suppose one of those laser-lookin' thermometers that you point at stuff is my best bet eh?.. would i just point it at the block? where would i buy one of those things?

Advanced Auto parts has a cheap one for $49.95 it's purdy good unit for a DYI'r!I got mine from a traveling tool man about 10-12 years ago,it cost allot more than that!!

Shoot it at the base of the thermostat housing!!

 

[CorvetteArchives]

.. don't you have to pull the tb's out (crossfire)? .

No you dont so dont let the shop try to ream you on labor. You just have to remove the COVER assembly. Easy... just like changing the air filter then just the rest of the air cleaner assembly PLATE surrounding the TB's.... easily unscrews. No TB removal is necessary

 

[geekinavette]

one more question for the masses here before i take it in today... the guy at the shop is pretty adamant that the sensor we need to check is on the left side of the engine... its the socket type one... but the sending unit should be the blade type one on the passenger side someplace right? one of the guys that is working this thing seems about as retarded as my timing and i want to make sure.

You have three temperature sensors...
1: temp gauge sending unit; driver's side cylinder head (single wire)
2: cooling fan switch; passenger's side cylinder head (single wire)
3: Coolant Temp Sensor (provides engine temp to ECM); front passenger's side of intake manifold (kinda tucked up underneath the AIR pump valve)

i was looking at putting in an aluminum radiator after payday. but on an '84 you have to upgrade the condenser or something to make room for it.

Nope...I put a Dewitts aluminum radiator in mine with no problems.

After reading all of this thread it really sounds like there is a sending unit problem. The engine temperature just can't change as fast as it sounds like you're describing. Plus...if that temp really did hit 299...well suffice to say you would KNOW it without even needing a gauge.

I had a similar issue when I bought my basket case '84. Some bubba actually had the O2 sensor and temp gauge sending unit wires crossed! How is beyond me as they are two completely different connectors. It acted very similar to what you're describing. I think I'd print out some wiring diagrams and start veryifying connections, who knows!

You can find wiring diagrams here: misterbill.homeip.net - /vette/wiring/

Bill