First Supra a few questions

[Rev Clown]

I just bought my first supra it's a 1992 targa top 5 speed 7mgte. The first thing is the stock radio was installed when I bought the car and the radio will say on after the key is off and out I have to remove the fuse to turn it off does anyone know what is causing this? The second thing is the car had 125,000 original miles and it sounds like there a slight knocking around 1500-2500 range and it's the loudest around 2100 and then it goes away around 3000. Could this be a rod knock or is there something else I should check before safely saying its a rod knock?

 

[MightyAl]

On the radio I would check the connection. It sounds like someone had an aftermarket in there and miswired the acc and battery wires. Pull it out and make sure no one has messed with the wiring before going much further.

 

[hvyman]

Did you push the lock button and turn the key all the way off?

Get a stethescope and listen around the engine. A video will help as well.

 

[IndigoMKII]

Did you push the lock button and turn the key all the way off?

Get a stethescope and listen around the engine. A video will help as well.

Or even a piece of hose if you don't have a scope.

 

[ttsupra2503]

It sounds like a bad wiring issue on the stock radio. Most likely to make it work they hooked up the acc wire and the battery wire to the same main battery wire. It should be hooked to the acc wire that will be come live when the ignition is turned to acc or on positions.

Is the knock worse when the engine is cold? Can you unhook one cylinder at a time from the ignition while running and see if any one of the cylinders gets REALLY bad? Basically if you release the pressure from the piston if you have a wrist pin or rod knock it should get much worse when you unhook the spark plug wire.

 

[supraguy@aol]

Um.
I think the knock is supposed to disappear when you pull the spark plug wire to the affected cylinder.

 

[7M4EVR]

Knock should stop if you pull the a park plug to the cylinder...and for the radio, you have to turn the key all the way off. The key can still come out even if it isn't all the way off

 

[ttsupra2503]

The sound gets worse when you release the pressure of the ignition pushing down on the system. Last time I tested a vehicle like this with a bad bearing it sounded like the rod was gonna come through the side of the block. it freaks you out when it happens.

Just wondering, why would it go away? whats the reasoning behind this thinking?

 

[Rev Clown]

Ill try unplugging the ignition wires one by one and see what happens. I took the stock radio out and it definitely had an aftermarket deck before because the wires are all reconnected by being twisted together I'm gonna be putting an a/m deck in anyway so ill just leave the radio out for now

 

[Maple191]

The sound gets worse when you release the pressure of the ignition pushing down on the system. Last time I tested a vehicle like this with a bad bearing it sounded like the rod was gonna come through the side of the block. it freaks you out when it happens.

Just wondering, why would it go away? whats the reasoning behind this thinking?

That only happens on SEVER conditions. Under small to moderate, the noise goes away.

 

[7M4EVR]

? When u cut the spark to a cylinder ignition does not happen. If there is no ignition in the cylinder the rod and piston are not compressing, so the noise stops. This should happen in every case unless it is a bearing issue where the crank turning would still cause the noise regardless of spark to that cylinder. That is my thinking anyway.

 

[Maple191]

? When u cut the spark to a cylinder ignition does not happen. If there is no ignition in the cylinder the rod and piston are not compressing, so the noise stops. This should happen in every case unless it is a bearing issue where the crank turning would still cause the noise regardless of spark to that cylinder. That is my thinking anyway.

If the damage is sever it will not go away. Usally the crank and sometimes are unsalavagable at that point.

 

[Rev Clown]

Ok I tried unplugging the ignition wires one by one and revving it a few times each and the sound did not change at all, it did not get worse and it did not get quieter or go away. So I'm wondering what I should do now

 

[Rev Clown]

I tried taking a video this is fully warmed up with all ignition wires connected.

[video]http://s1177.beta.photobucket.com/user/skillzerozx11/media/IMG_1135_zps5c78e557.mp4.html[/video]

 

[7M4EVR]

Do all this and come back with some more info...try using a block of wood, rubber hose, screwdriver handle, or actual stethocope to narrow down where it is coming from, but do it quickly and STOP revving the shit out of it! If it is knock your only doing more damage to things. Check the crank pulley bolt to make sure it is tight. Check to make sure the clutch fan isn't hitting anything (pretty unlikely), then pull the valve covers off and check out the cams and check clearances. If you want to fix it you have to get dirty.

 

[Rev Clown]

Do all this and come back with some more info...try using a block of wood, rubber hose, screwdriver handle, or actual stethocope to narrow down where it is coming from, but do it quickly and STOP revving the shit out of it! If it is knock your only doing more damage to things. Check the crank pulley bolt to make sure it is tight. Check to make sure the clutch fan isn't hitting anything (pretty unlikely), then pull the valve covers off and check out the cams and check clearances. If you want to fix it you have to get dirty.

Alright I'll try to get most of that done tomorrow and I was only revving it like that for the video I haven't been running it at all except that

 

[Rev Clown]

I tried using a long metal file and hose to try and listen and when I touched the front and back of the valve covers I Hurd the motor humming as it should but when I touched the middle I could her a distinct knocking sound clear as day so now I'm thinking its just something with the valves any ideas?

 

[7M4EVR]

7m can be sneaky about knock. mine sounded top end but was actually bottom, so listen on the bottom end too. As said before...take the valve covers off and check clearances. A typical problem are the shims. Search it and you will find plenty of info on it.

 

[Rev Clown]

Alright I spent about 20 mins today while it was idling using a piece of wood to listen to all different spots and the noise is definitely the loudest on the center of passenger side valve covers. I'm gonna take off the valve covers this weekend is there anything I should look for like stuff that is common?

 

[7M4EVR]

Just be prepared to dig into it! When u get the valve covers off you will be able to see the cams and the top of the valves (lifters and shims). Maybe if your lucky and check clearances between the shims and cams you might find the problem. However you will most likely have to take the cams out and keep digging into the valves to find the issue, which opens you up to all sorts of more work. The term goes over proper procedure. Good luck!