Hey everyone, so this car has been a major headache between my misfire p0300 , the bucket tappets tapping away and now appears I have a coolant leak coming from the back of the engine, went over all the hoses and even got under the car and it seems like the leak is coming from the block right above the motor mount and the heat shield at the rear of the engine, I'm thinking I might have a blown head gasket, any input would be greatly appreciated, car is slowly falling apart and I'm running out of options....I have no overheating yet but the leak is quite constant and I keep having to refill my reservoir every so often.... could this have been the cause of my misfire all along ? Car idles very rough and loses power when mashing down the pedal

 

The P0300 is a random misfire.

Could be a large vacuum leak behind the MAF. Like the intake manifold gasket, or the intake tube itself. Clean the TB an inspect.

Or... if the oil burning is bad enough, the plugs are fouled causing a misfire.

Or.. if the coolant loss is indeed a bad HG, and you burn a lot of oil, that would surely cause a misfire. The plugs are soaked. Pull a plug for inspection. What does the oil look like on the stick, and under the oil filler cap? If its foaming up under the cap thats a sign its a HG. External leaking of coolant may be something else. rent a block tester https://www.autozone.com/loan-a-tool...ter/391378_0_0

What exactly does mashing down the pedal mean? Beating on it?

Get some pics posted. Its all guesswork, but places to start narrowing things down.

 

I'm wondering if maybe it could be the block drain plug leaking , are these prone to leaking coolant, like I said it's coming from behind the engine where the block meets the head, I checked all hoses around that area and they all seem to be good no wetness, it's leaking onto my exhaust and making all kinds of fumes ...as of yet there is no overheating, I'll have to check the oil cap and or the radiator cap for milky substance.....as for the misfire it's been doing it for a while now , I'll come to a stop check engine light will flash for a little bit and once I get the car going again it stops and stays solid .... I've replaced ignition coils, spark plugs and valve cover gaskets , if indeed I have a bad head gasket would this be the cause of the misfire just getting worse ... when I hook up the scanner the only codes that come up are p0300 and p1800 which is for the vias solenoid....by mashing the pedal meaning the car feels gutless, it's a 6 speed manual but I don't feel the power , it hesitates at first and then the power kicks in like it's starving for fuel

 

First, I'm not a mechanic. Have no history with Nissan. And I was able to replace the lower and upper intake manifold gaskets. I did it in a few hours with basic tools. Not expensive. I would begin replacing them. Get that ruled out. And it gives you a chance to inspect all hoses, plugs, coils, see in back. Soak the piston tops and spray the ports with some type of spray cleaner. Also, any type of water issues getting on the knock sensor will definitely cause issues with ticking. You get a chance to see whats in the middle. After doing that I found out it was a bad friggin coil causing my P0300. Turns out depending on its location, it can appear as a P0300, or the actual cylinder. I bought the Hitachi off Amazon, recommend you get one anyways. These coils are 2 piece. The top, and the extension that goes down to the plug. So just pulling them off can damage them. Use plenty of bulb grease thats for sure.




Took the TB off to clean properly. Check the coolant lines connected to it. Nasty oil burner. Look at the oil backed up in the intake.



Upper/plenum off. Not hard at all. Need this steps for plugs, anything in back of engine. Some pics for you to see back of engine.



Upper/plenum and lower off. Down in the center is the knock sensor. It was flooded out, full of debris. No doubt that was a source of problems for pinging, ticking, etc.



Anyone that tells you oil burning long term is not a problem are lying to you. No doubt this engine was misfiring on all cyls. Imagine the catalyst on this car is bad as well.



Throttle body full of oil. No doubt this engine was misfiring huge. Just because of its appetite for oil.

 

I cant recll did you do the valve covers too?
Oil leaks into the wells on those i heard.
If you service the TB on the 01 you have to reset the tps closed position then an idle relearn.
Is there a reset procedure for the 02? I read it has an IVT.

 

Like I said in my first post, I've replaced both valve cover gaskets , intake plenum gasket and replaced all the spark plugs with new ones , your right it's not hard to take the plenum off , after doing it a couple times I have the process down to a "t" ...couple houses here and there , bolts , harnesses and it's off , nothing really to it after your first couple times ....btw I also replaced all coils and I bought them on Amazon but they were aftermarket ones not the Hitachi ones so perhaps my misfire could be cause by one of those being bad , as for the ticking, it's the bucket tappets, the gap between the cam lobe and the tappets increase over time causing the obnoxious tapping sound on idle and gets faster with rpms, the only solution to that would be to change our the tappets with new ones .....my concern here is the coolant leak , I can't determine where it seems to be coming from , is there a block drain plug on the rear of the block that could be leaking ? I've checked all hoses but nothing

 

ok. Nothing leaking in the heater core area?
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