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Jay, Nissan Technician
Category: Nissan
Satisfied Customers: 20504
Experience:  20+yrs experience with Nissan & Infiniti Trained & Certified.Currently still working for Dealer
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I have a 1986 Nissan D21 Hardbody 4x4. It was over heating

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I have a 1986 Nissan D21 Hardbody 4x4. It was over heating intermittently. It never totally overheated. So I replaced the thermostat and the water pump. It hasn't overheated since, but now it runs really rough when it is cold. After it is warmed up it doesn't have problems.

Hello my name is ***** ***** thank you for your question.

How long does it run ruff when first started?

Customer: replied 1 month ago.
It runs rough until it gets up to temp. Sometimes you actually have to rev it because it wont stay at idle. Then if you try to gun it, it bogs down and quits. My son said it was smoking this morning and i don't remember it doing that before.

If you pull the spark plugs out, and look down at the pisitons, are any of them looking fairly clean? You should see a layer of carbon on them. So you really shouldn't see any metal. Also let me know what brand spark plugs you have installed?

Customer: replied 1 month ago.
NGK plugs B6HS, The pistons seam to have a layer of carbon on them. No metal that is all that visible.

Ok.. That is good with the plugs.. I am thinking that you may have a bad head gasket. When the truck cools down, coolant seeps into the cylinders and that is why it runs ruff when first started. I would have it checked to verify.

Customer: replied 1 month ago.
would a bad head gasket reduce gas mileage or make the truck burn oil? It doesn't have leaks but needs a quart or 2 every month.

A clogged PCV valve can cause a oil consumption issue which could effect Miles per gallon.

Customer: replied 1 month ago.
Ok i will check those out. Thanks for your assistance

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Thanks Jay!

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