Questions and Answers
That Nissan Truck Returns
Q. Hi Vince, How are you doing? Well, my truck has a persistent problem and I need your help again.
Vehicle: 1990 Nissan pick up truck, 4 cylinder KA24E, 5 speeds, electronic fuel injection, 2 WD, no power steering, no A/C, 150,000 miles.
Problem: Coolant loss due to internal leak to engine oil.
Vehicle repair history: Six months ago, the timing chain was making rattling noises due to broken chain guide on driver side. I removed and installed the new timing kit. But after few days of driving, I noticed the coolant level in the radiator and the reservoir was low. Every two weeks, I have to fill in at least half gallon of coolant. The engine oil has a dark brown color and a little thin. The truck timing and rpm are good and stable. The heating system is good. There is no smoke in the exhaust. There is milky residue in the oil cap. My truck did not have coolant loss prior to the timing repair job. I did remove the timing cover and visual inspected for cracks but did not see any damage. I removed the timing cover and reapplied the silicone gasket maker (Nissan made). The cover has 8 bolts (10 & 12 mm) and I torqued each on 12 ft/lbs in a cross pattern. I have done the rework three times and the leak still exist. Is this leak from the timing cover, coolant jacket common to cover and engine block jacket, connecting hoses or blown head gasket? Could you please show me the direction of how to trouble shoot the source of leak and fix it.
Thanks for your help.
A. Oh, I'm just peachy Jeff. Three of my chinchillas decide to give birth at the same time and now I have ten baby chins running around the house. I'm getting to old to chase kids anymore.
I think what we have here is a bad head gasket. Common for this engine at this milage. There are two ways to determine this, neither one I believe you have at your disposal. One way is to run the engine with the radiator cap off and using an emission analyzer, see if there are any hydrocarbons in the cooling system. You can buy a test kit for this, but I never had much faith in their reliability.
The other way is to connect compressed air to each cylinder in turn and see if there are any air bubbles in the radiator or leakage between cylinders. Usually when the head gasket blows, it either blows between cylinders 3 and 4, or blows out the back.
I have never seen that timing chain cover crack, well, I did once, when I tried to pry one off and forgot to remove a bolt. Okay, I screw up once in a while too. Anyway, that's not to say the cover couldn't have a crack that you can't see. The milky residue you see on the oil cap is a common symptom of a bad PVC system.
I think at this point you have done all that you can. You can take a shot at replacing the timing cover, but I don't think that's it. I would recommend taking it in and having the head gasket checked. Let me know what happens.
Additional Information provided courtesy of AllDATA
