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Discussion Starter #1
I recently honorably discharged from the Marines after 4 tours so money is tight. I own a 1996 4Runner, 3.4 L 6V, 198,000 miles. About 3 weeks ago the check engine light illuminated I checked for codes and saw PO303 OBD code indicating the #3 cylinder. I checked the number 3 cylinder and noticed the plug was loose and dirty purchased a new plug and for 3 weeks it was running great. I then noticed white smoke coming from the exhaust after I exited the freeway. There was a cloud. I then drove the vehicle home and saw that the smoke almost completely dissipated. The next morning I started the vehicle and saw white smoke coming from the exhaust and I could smell gas order. l checked to make sure the new plug was not loose.
My wife did say she noticed the reservoir was low and she did add antifreeze to the overflow container. I think it's a head gasket or a crack block. Any thoughts on what the problem is?
 

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short-throw dipstick
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5,935 Posts
Usually BHG on those. Not a difficult job if you want to DIY, just takes lots of time.

But check first, rent a color-changing combustion leak detector from AutoZone or equivalent and see if it's really that.
 

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2016 Corolla S Prem
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3,616 Posts
+1
The 3.4 had a recall for the head gasket back in the day.
Check your oil for "milkshake" and coolant smell, and check your radiator for oily residue.
 

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short-throw dipstick
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5,935 Posts
+1
The 3.4 had a recall for the head gasket back in the day.
Check your oil for "milkshake" and coolant smell, and check your radiator for oily residue.
Did they ever update the head gasket design like they did on the later 4.0s?
 

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1998 T100 SR5 2WD
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13,562 Posts
Welcome to the forums! :)

Was there any maintenance performed prior to this issue? ;)

A few things you can do:

Pull the spark plugs and check their condition. The super clean one (with the exception of the new plug you put in) will have been steamed cleaned and that will indicate that coolant has been gitting into that cylinder.

Using a coolant pressure tester, pressurize the cooling system and monitor the pressure gauge. If it drops, there stands a good chance you have a bad head gasket. With the spark plugs out, you can probably hear or see the coolant escaping into the combustion chamber. Other areas that coolant can git into the combustion chamber is via the IAC (idle air control) valve gasket. If the valve was removed fer cleaning or inspection and the gasket was pinched, there is a good chance that coolant is being sucked into the combustion chamber. Another area is the intake manifold gasket. Yer local auto parts store like AutoZone will probably have the coolant pressure testing tool fer free rental (deposit refunded after the return of the tool) or you can purchase one from Harbor Freight fer about $90. ;)
https://www.harborfreight.com/radiator-pressure-tester-kit-63862.html

If you have an endoscope that wirelessly links to a tablet/smart phone, that would be good to inspect the combustion chambers. You can find them on Amazon fer under $30. ;)
 

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Discussion Starter #7
Thank you, everyone, for your comments but I'm breaking down and taking 4Runner to get a diagnostic check or whatever they have to do to tell me what the issue is. I decided that I am not putting more than $600.00 into the repair. I'll sell it and buy an SUV with fewer miles and a little newer. I will let you know the outcome
 
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