Smoke coming from under hood, Issues please help.

[BrianZ32]

Hello everyone, just recently ran into some issues with my 90' Z NA
Just recently, i ran into a problem where the car would overheat in traffic while AC was on so i took it to a local mechanic and they diagnosed it as being the radiator. I have yet to replace it but now, just these last 2 days, the car has been having an irradical idle. Even when parked, it goes up and down between 1000-1400. When starting the car in the mornings, it starts off at the high 1800s and works its way down to about 800 when it stabilizes. Today i popped the hood to find small amount of white smoke towards the top of the car. Mainly by where the hoses were. I can also hear little pops as the idle goes up and down while parked. I have notice a slight amount of performance loss as well. I recently did a tune up about 2 months ago and installed a pop charger about 1 month ago. My car has 149k miles and it is an automatic. I dont have many ideas of what the issue can be. If anybody can help, i would appreciate it as it is frustrating not knowing what the issue is. Sorry for the long essay, im just trying to give as much detail as i can to give a better idea.

[rgregoryb]

First of all you need to run the ECU codes for a starting point.

[BrianZ32]

First of all you need to run the ECU codes for a starting point.

I ran the ECU and everything is fine, code 55

[rmlamp]

You need to identify what kind of smoke it is. I.E. coolant or oil.

[elecfus]

your mechanic probably did a radiator pressure test on the car. this test involves removing the radiator cap and applying pressure to the coolant system. they then watch a gauge to see if the pressure drops. if it drops then there is a leak. they also would have done a visual inspection on the coolant. you cant tell by looking through the top but if you remove the lower radiator hose and collect it in a tray you can see if your coolant is old and full of rust. it wont be a bright red or green color if so. it turns yellow or brown depending on the engine content of the water. check around the edges of the head gasket, where the heads meet the block. if there is black sludge there then your head gasket is leaking.

it might not be the radiator but there is a coolant leak. your engine is overheating. dont drive it.

the pinging or ticking sound and rough idle are your heads being warped out of shape. engines often recover mostly once the cooling system is repaired.

when was the last timing belt and water pump kit done? the service interval is 105k km although people often leave them longer. your 150 000 milage indicates that it was due for its next timing belt kit a while ago. look around the inside of the bonnet, engine or windshield for a sticker saying when it was last done. with an overheating engine it's a good idea to go ahead and do a timing belt, roller and pump kit along with the hydraulic bearing in the fan. get a good kit like a gates, dunlop or denso. fancy after market brands tend to use cheap chinese replicas which may or may not last the whole interval. its only a few dollars more and will last you the rest of the life of the car. you can inspect the timing belt by openning the little 1" wide circular flap on the timing belt cover, that big black plastic thing behind the serpentine belt. worn belts dont always show wear but if there is visible wear then it is long overdue. take a photo for us.

you should also look into replacing all the coolant hoses because overheated coolant stresses the rubber and causes leaks. start sourcing the hoses. here in australia, some of the hoses were strange sizes so I had to use metric oil and transmission lines and $40/m hydralic hoses for the AIV system. it's OK to use nitrile hoses where EPDM rubber is used because nitrile is stronger and more resistant. oil will eat through EPDM and burst the low pressure rated water hoses though. make sure you get hoses that will fit over the barbs as high pressure rated hoses wont stretch like un-reinforced water lines.

[elecfus]

there are also some other things you can do that may or may not have an effect. replace the fuel filter at the same time. there is a magic bottle often labelled "fuel system cleaner" this is nearly always a special type of soap that you add to the gas which cases water in the fuel lines to emulsify, that is, mix like how adding soap to the dish water breaks up oil and makes it form tiny little beads. this helps the fuel injectors pass the water in the fuel system. you add it with a full tank of petrol and gently drive it until the fuel light comes on then just fill it as usual. this doesnt actually do any kind of cleaning to the system other than removing water but if you dont want to mess around with a plenum pull then its an easy fix if that is causing problems. a lean engine from water in the fuel can also cause overheating.

[evildky]

I'd start by replacing the known bad radiator, there are small coolant lines running under the plenum, most likely one of them sprung a leak, you can bypass them but continuing to drive a car that had a bad radiator is asking for trouble.

[BrianZ32]

your mechanic probably did a radiator pressure test on the car. this test involves removing the radiator cap and applying pressure to the coolant system. they then watch a gauge to see if the pressure drops. if it drops then there is a leak. they also would have done a visual inspection on the coolant. you cant tell by looking through the top but if you remove the lower radiator hose and collect it in a tray you can see if your coolant is old and full of rust. it wont be a bright red or green color if so. it turns yellow or brown depending on the engine content of the water. check around the edges of the head gasket, where the heads meet the block. if there is black sludge there then your head gasket is leaking.

it might not be the radiator but there is a coolant leak. your engine is overheating. dont drive it.

the pinging or ticking sound and rough idle are your heads being warped out of shape. engines often recover mostly once the cooling system is repaired.

when was the last timing belt and water pump kit done? the service interval is 105k km although people often leave them longer. your 150 000 milage indicates that it was due for its next timing belt kit a while ago. look around the inside of the bonnet, engine or windshield for a sticker saying when it was last done. with an overheating engine it's a good idea to go ahead and do a timing belt, roller and pump kit along with the hydraulic bearing in the fan. get a good kit like a gates, dunlop or denso. fancy after market brands tend to use cheap chinese replicas which may or may not last the whole interval. its only a few dollars more and will last you the rest of the life of the car. you can inspect the timing belt by openning the little 1" wide circular flap on the timing belt cover, that big black plastic thing behind the serpentine belt. worn belts dont always show wear but if there is visible wear then it is long overdue. take a photo for us.

you should also look into replacing all the coolant hoses because overheated coolant stresses the rubber and causes leaks. start sourcing the hoses. here in australia, some of the hoses were strange sizes so I had to use metric oil and transmission lines and $40/m hydralic hoses for the AIV system. it's OK to use nitrile hoses where EPDM rubber is used because nitrile is stronger and more resistant. oil will eat through EPDM and burst the low pressure rated water hoses though. make sure you get hoses that will fit over the barbs as high pressure rated hoses wont stretch like un-reinforced water lines.

Im pretty good and being able to pick up on coolant, i have not been able to smell any lately but my first assumption was that there was some type of leak. I have only had the car for a little under a year so i am not 100% sure when the timing belt was done, but there was a nice stack of service records i can look through. I replaced the fuel filter at the time of the tuneup. My mechanic did mention that the hoses were old and brittle...

[BrianZ32]

I'd start by replacing the known bad radiator, there are small coolant lines running under the plenum, most likely one of them sprung a leak, you can bypass them but continuing to drive a car that had a bad radiator is asking for trouble.

This will make me sound like a total noobie, but what is the difficulty level for replacing the radiator? I have not had much hands on with my car...

[elecfus]

it could also be oil dripping on the turbos. idk, my heads not in your bay. look around the radiator seals maybe? thats where i tend to look for a bad radiator.

they're very easy. it's about four bolts and then matching a hose to them. the new radiator might not match the hoses but you can get a piece to clamp on to match the hose sizes.
while its out you can replace the transmission cooler hoses and dump the old transmission oil which might be due for replacement. I do it anytime an engine overheats and tend to find it comes out black.