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Thread: mystery smoke

  1. #1

    Default mystery smoke

    Alright, here goes:

    For the past fifteen months I've been under the hood of the 86 GT fixing various things like coolant leaks, oil leaks, and overheating issues. I replaced all major gaskets and that solved the leak problem. I broke a water pump bolt and had to drill it out. Drilled into the block and coolant flowed out. Plugged the hole with high temp red sealant and permanently installed a threaded stud so as to attach the water pump. Ok there.

    Flushed the cooling system with a home made pumping kit- did the radiator also. Car still runs hot but doesn't lose coolant. Car does not overheat but the gauge reads to the high side more than not.

    Engine still runs hot. After only four or five minutes when the thermostat opens the underhood temp is unbelievable. Too hot if you ask me.

    I replaced the distributor as I felt the high heat may have fried the PIP. I had to reset the oil pump drive shaft to reinstall the diz. It came out of the pump when I removed the diz. I relocated the TFI module to the passenger fender. That project actually went well.

    I replaced the air diverter valve and the one way metal check valve that route air to the heads. I replaced the tube also. It is properly secured and clean. I used a mirror to examine the passages on the cylinder heads. They have a light coating of carbon only.

    Car ran lean according to the computer. This was a grounding issues as two ground wires were missing. I replaced the main ground strap at the rear of the drivers side of the engine and the ground wire from the two ten pin connectors that grounds to the fire wall. No more lean codes. But then I had 44/94. Thought the new diverter and one way valve would take care of that.

    I haven't ran the thing enough to get codes lately. Still too hot for me. And now I have SMOKE from the oil dipstick tube. First for me and I'd say very serious. Last summer the car passed both KOEO and KOER self tests and the compression test.

    I trimmed about a half inch off the factory PCV hose and made sure it was on the PCV valve when I reinstalled the upper intake. Hose was cracking a little. It won't go on any further. I pulled the dipstick out and it wiped oil and looked like most of the oil was still in the engine. Can't say I smelled coolant or fuel.

    Car has NO throttle response but a decent idle. The throttle cable is routed behind the intake and has some tight curves but doesn't appear that it can be routed any other way.

    All vacuum lines are on correct and double checked. It sounds good at idle but I refuse to drive it anywhere.

    I've put maybe ten miles on the car in fifteen months and it appears I am no better off than before.

    What might the problem be? What should I expect? I would guess at this point I'll be yanking the engine next. It has 40,000 on the rebuild which was about 18 years ago.

    Thanks FEP.

  2. #2


    What condition is the radiator in? Inside and outside? Also the fan clutch if original probably lost all the viscous oil by now.
    If you actually have a lot of smoke from the dipstick tube that’s blow by and your rings are not sealing. Either they are worn out or seized with carbon.
    84 LX Vert. 5.0 5speed canyon red on white
    99 cobra, electric green on medium parchment, vortech s-trim

  3. #3


    It wasn't a great deal of smoke but enough. I will check compression this week as well as replace the pcv valve. The radiator was cleaned out this spring and doesn't leak. I still have a full load of coolant. It appears clean. I'll check oil this week also. And the plugs. Hopefully I can pull some codes.

  4. #4


    Was it Cleaned out by a radiator shop? Or a home made flush kit? Have you removed to inspect it? How are the fins are they all intact or corroded and missing rows of fins? On the fan are you running a new clutch or electric? If the coolant is full the head gaskets are good, the pump is new and the thermostat is opening your issue is in the radiator or lack of airflow over it
    84 LX Vert. 5.0 5speed canyon red on white
    99 cobra, electric green on medium parchment, vortech s-trim

  5. #5


    I cleaned the radiator out myself with a home made flush kit. Worked well and even flushed the block. Radiator is in good shape, not damaged or missing fins. Flow appears good. I need to actually run the car around beyond the driveway to be sure but if anything, at this point I'd say the clutch is likely shot. Fan is in good shape. I'll check it this evening. If I recall, it moves freely when cold.

  6. #6


    Just checked it. It moves easily but doesn't keep turning, maybe one quarter before stopping. Ever so slight resistance.

  7. #7


    If you cruise at 40mph and it doesn’t run hot then starts to overheat when stopped then it’s a safe bet it’s the clutch.
    84 LX Vert. 5.0 5speed canyon red on white
    99 cobra, electric green on medium parchment, vortech s-trim

  8. #8


    Right now I'd say the clutch is best replaced. The fan moves somewhat freely cold or hot.

    I checked compression today. All cylinders are at either 120 or 125 psi. Phew. I also had to replace the pcv valve tube as it was completely off the valve. Had some vac hose and installed a section and now no vacuum problems. Plugs all looked good, too. I checked timing but couldn't locate the mark on the pulley with the shunt removed and the light hooked up. Car idled very low when I did that. With the shunt replaced the computer is taking care of timing. Checked with the shunt in and its good. May be a problem there somewhere. New diz seems to be fine but I have it rotated beyond what it should be. I relocated the TFI module and if it were still on the diz the diz wouldn't move as far as it is now. But the car runs and sounds good.

    But still hot. Very hot. It did take in a little more coolant. May have been some trapped air somewhere. Car sounds good but no road test. However I did try to get codes. KOEO shows eleven. All systems go. KOER shows only 44/94. I'm at the same spot I was two months ago. I'd guess that smog pump air is still going upstream and not switching to downstream. Since the thing is hot now I'll try again this evening and see where the air goes at the diverter valve, which is new as is the one way check valve for the upstream metal tube to the back of the heads.

    I should road test it but I'm a little hesitant right now.

    Am I on the right track? Let's hope so. Thoughts appreciated. Maybe this fox will hit the pavement soon.


  9. #9


    Pull your advance stub.

    turn the distributor until the motor speeds up then back off timing advance until it slows back down then back up just a little bit. It should not crank hard when you start it with the advance hooked up.

    now get some correction fluid and a wire brush and find your marks and try to make sense of where your timing is. Pull the stub again and use a light. 86ís with E6 heads and VM1 ECU will only tolerate 13.5 degrees of advance before they overcome the cooling capacity of a NOS OE radiator or freshly rebuilt and pressure flush.

    I went to a 3 row OE style radiator years ago. These days Iíd look at the FB169 ó thatís what Iím running on my 86GT now.

    if your fan clutch doesnít have heavy drag itís bad. Get a clutchless reverse rotation blade and test it, or go electric

    make sure you did not use any Teflon tape on the temp pickup and only use Motorcraft. NOS is possible.

    Coding lean can be too much advance or low fuel pressure or even an exhaust leak

    more or less on the right track Iíd say.

    personally the emissions crap on my 86GT never gave me any problems. Iím near 1/2 million miles. It is a decent hunch but if things are stuck it will stumble at idle badly as EGR pumps exhaust back in.
    Last edited by erratic50; 07-14-2018 at 03:03 PM.

  10. #10


    I may have missed it in the replies. I didn't read them all word for word. But all I recall in the original post is you said "too hot if you ask me" and the "gauge reads high" Do you have a reading of the temperature that the car is running using a real gauge? You said you are ready to pull the engine so I can't imagine that the purchase of an accurate temperature gauge would be that large of a setback. I do apologize if that was covered already. I did honestly skim the replies without reading them all. I just feel like it would be nice to have a REAL gauge (not a 30 year old fake one like they came with) tell us the temperature of the engine.
    Last edited by homer302; Yesterday at 06:39 PM.

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