Did you do the radiator bypass with the trans fluid where the trans fluid goes through the bottom of the radiator? Check your trans fluid. Does it look normal or like a strawberry milkshake?

When my trans took a dump because of the radiator leaking into the trans fluid, the TCM fried. When the TCM fried, it blew a fuse keeping the ECM from functioning. It would not start. Replaced the fuse, overhauled the trans, put in a new TCM, bypassed the radiator trans cooler to a separate cooler and all is well.

 

First a few more questions. .
Does the starter motor spin the engine?
Next, check the oil. is it overfilled? oil floats on water so if you cooked the engine bad enough to hurt something (head gasket, head, block) and it is dropping water into the oil pan you will get a high crankcase level. If it ran enough in this condition it makes tan goo that looks like a milk shake. If it just dropped it in with little or no running it will go to the bottom and raise the oil level that you will see on the dipstick.

 

Yes the starter spins the engine when starting. Unless you have a old fashion crank. Or a pull cord.

The water and oil will mix pretty damn quick and become a milkshake.

 

Did you get the timing right? Dump question but sometimes it's the little things.
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The starter is spinning.

I changed the oil and it is fine. I have it saved. I had no additional volume.

The radiator was leaking where the top plastic tank was crimped to the aluminum.
I tore open the bottom tank and the internal aluminum tank where the tranny fluid circulates was ok.

I never removed the main or secondary timing chains. To remove the water pump you have to pull the tensioner out to slack the chain.

I think that I either an oil sensor or water temp sensor that is shutting off spark or fuel?

 

^^^^ Check his points, including compression. I once blew a water pump on a Chevy just as I was entering the Holland Tunnel in the summertime. With no water circulating, and no cool air flow, the head gasket was destroyed. While I was able to limp home without shutting off the engine, it would not start after that.

 

read the codes

Read the Codes P0340 camshaft position sensor bank A
P0463 Fuel level sensor circuit high bank A

 

Fuel level I am not too worried about right away. Cam position sensor is something to look at. My gut tells me the cam timing jumped and that is throwing the valve timing off and tossing the code. Or maybe luckey and it is just a bad sensor. To tell the difference clear the codes and without cranking the engine over check for codes again. If the cam sensor shows up again it is a bad sensor or wiring. If it only comes after cranking the engine over trying to start it then it is picking up that the cam is out of phase with the crank. Hopefully it isn't so bad that valves hit pistons.

 

I will try that. I just removed the sensor. I had to stand on my head.
I felt inside the hole and didn't feel good. Something jagged.

I removed the other sensor and it felt nice and smooth.

If I was feeling the back of one of the camshafts it is broke.
Will probably be removing the valve covers.

 

I cleared the codes, turned the key off and waited 60 seconds or so.

Turned the key back on and read the codes. Only getting the code for the fuel level sensor which is a known issue. The fuel gauge hasn't worked for a year.

I will pull the valve covers off this evening and survey the valve train. And take everything off the front again and this time remove the timing cover.

 

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Good Luck

 

Need to find out if you're getting spark, maybe something went haywire with the ECU. Some shops may have a probe they can hover over your spark plug coils during engine-start to sense if the coils are even functioning.

If you have another Xterra you can swap ECU's with, could be worth the try. My ECU took a sh** in my 05 nismo auto frontier when it had overheated once after the dealer improperly refilled my coolant. Everything checked fine as far as diagnostics go but no triggers were being sent to the coils to fire spark to the spark plugs... dead ECU.

Other possibilities...

maybe a throttle body failure? I know coolant runs through the throttle body, I don't know if it required the coolant to be in the throttle-body but maybe running out of coolant could have caused it damage.

Turning the key to the "on" position before starting, make sure you are hearing the fuel pump in the tank purring for a couple seconds before you turn the key over to start the engine.

 

If you have fuel and haven't verified spark and the cams aren't busted, the coils getting burned is a real possiblility. I had a small 4cyl overheat once and it ruined the coils. If those windings get too hot they can go bad. Would be a nice cheap fix compared to a new cam and valvetrain.
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^^ I will bet on that as well. And cross fingers that burned up coils didn't muff the ECM/ECU. Don't dump tons of money into what doesn't need to be done, roll out all the simple computer/electrical related stuff first.

 

I finally got back at it. I pulled the intake collector off and the passenger side valve cover.

I the valve train looks ok, actually pretty good for 125,000 miles. The rough slot that I had felt through the position sensor hole is actually cut in the cam. There are several. I think that the position sensor reads them.

I turned the engine over by hand every thing looks good and sound right.

I am going pull the other valve cover and the timing cover tomorrow. I will check the valve timing by the book. I am also going to replace the secondary timing chain guides. This motor has the old style guide that has been updated.

I am also need to check the oil pump. When we were limping home their was a squealing noise that I assumed was coolant on the belt. At this point I have enough torn apart again to be thorough.

I still think that the problem is lack of spark. I could smell fuel in the exhaust when I was cranking the motor.

the good news is that I cannot find anything wrong
the bad news is that I cannot find anything wrong

 

Any news on this one?

 

yeah I have been busy, But I am tearing in to it the rest of this weekend

I will post what I find. I did pull the plugs and they had fuel on them.

I am thinking spark, but I am going to pull the timing cover off today and check the chain. I also am going to check the oil pump for my own peace of mind,

 

good luck man. Sounds like you have had a rough go of it, but you are getting there.

 

Well I finally got half a day to work on it. The timing chain is off by about 8 links on the crank. My suspicion is that the chain tensioner lost oil pressure.

The chain slacked and spun.

I am going to take the oil pump out and open it up. It will be a couple days before I get to it.

I have located a 2006 engine at a junk yard, they do not have the mileage, but they got the wreck in 2006. So I am thinking between 100 and 30,000 miles.

They want $2,000. That may be the way to go.

 

That's much cheaper than new if it actually was wrecked in 2006. I would make sure it can be turned over by hand first. Then it's a matter of maybe getting a scope to view the cylinders and making sure that it doesn't need a rebuild from sitting so long. I think it would need the cylinders honed to get surface rust off and new gaskets. Still cheaper than new. Good luck.

 

Timing Chain

On page 46 of the EM "Engine Mechanical section of the service manual" it shows the timing mark on the main pulley aligned with the mark on the water pump cover. It also shows the position of the cam lobes for Cylinder 1 TDC.

When I had the main pulley aligned my cam lobes were not in the correct position. So turn the engine a complete revolution and check again. Still incorrect.

I removed the timing chain cover.

Page 63 of the same manual shows the relationship of all the three timing chains and all of the marks. The marked links on my timing chain did not matches the marks on the sprockets. My first thought was that the tensioner had slacked and the crank had rotated without the chain.

I removed the spark plug for the number 1 cylinder and inserted a dowel rod.
I used the dowel rod to determine when the piston was at the top of its travel. TDC

I was able to get the cam lobes in the proper position and the piston at TDC.
All of the timing marks on the various sprockets are in the correct position although the gold and copper links on the chain are not correct. The crankshaft key matches page 63 which is to the left of straight up. The crankshaft key matches the first timing mark on the main pulley.

This does not agree with the position shown on page 46.

I don't know how to insert a pdf image of the manual pages.

I initially thought that since I could not get the cam lobes in the proper position when the main pulley marks were aligned with the marks on the outside of cover that the chain had slipped and that the crankshaft was not in proper relationship to the cam shafts. The ECM didn't like the input from the crankshaft position and camshaft positions sensors and was not sending a signal to the coils.

Now it appears that the crankshaft is in correct relationship to the camshafts even though the marks on the chain are not correct. If you move the chain forward 6 links on each of the 3 sprockets then it still has to work.

I still need to check to the oil pump. I wanted to be satisfied that I understand the timing before I pull the chain and sprocket off.

Looking for guidance.

 

I downloaded a Haynes Manual. It shows a timing mark located on the belt tensioner bracket. This mark agrees with page 63 of the Nissan Manual. I stood everything up on my bench and took a picture. The mark on the water pump cover page 46 of the Nissan Manual is not even visible when you have the belt on the motor.

Mystery solved.