Well, sort of. This weekend I took the old engine apart. Worked for about 2 hours Friday evening and 3 hours Sunday. Friday I got the timing cover(s), chain, water pump, valve covers, exhaust manifolds, cams, lifters, oil pan(s), etc off the engine. Sunday I got the heads off and took the pistions, rods, and crank out.

 

As to the failure...

Cylinder 5 is the one that lost (some) compression (down to 100psi). I knew I lost compression on the intake valves, but didn't know where else.

Cylinder 5's head:

http://www.ericj.org/maxima/img/vq_t.../cyl5_head.jpg

You can see on the left (by the intake valves) where the head is pretty beat up from the screws. The valves themselves look 'ok', but I won't know more until I take the head apart (valves out).

Piston 5:

http://www.ericj.org/maxima/img/vq_t...pistion5_1.jpg
http://www.ericj.org/maxima/img/vq_t...pistion5_3.jpg
http://www.ericj.org/maxima/img/vq_t...pistion5_4.jpg

Looked just fine.

Cylinder walls for cylinder 5:

http://www.ericj.org/maxima/img/vq_t...yl5_walls1.jpg
http://www.ericj.org/maxima/img/vq_t...yl5_walls3.jpg
http://www.ericj.org/maxima/img/vq_t...yl5_walls4.jpg

No signs of damage that I can see.

So, for the time being, I'm not 100% sure where the failure was. I'm assuming that one or both of the valve seats on the intake valves is damaged, but again, I won't know until I have the head apart.

All the bearings (crank & cam's) looked just fine. I cracked the oil pan at one point (could have been before I started taking it apart, dunno).

All the pictures here:
http://www.ericj.org/maxima/img/vq_teardown/

Zip of the pictures here (4.5MB):
http://www.ericj.org/maxima/img/vq_t...q_teardown.zip

 

do i smell a built motor in the works ?

 

Maybe a long way down the road, but otherwise no. I've already installed a stock motor, and don't have a need for a built motor.

But I'll never say never.

 

wow, great pics
is hte "new" engine giving u any probs?

 

No problems anymore. I had a starting problem and a vaccum leak, but I fixed the leak, and the starting problem just went away.

Boosting 9psi and its doing great!

 

does anyone know what the compression should be one a 95 maxima????

 

also where is the timing chain tensioner? is it the thing with two screws and the guide to the right of it?below the leftside cam shaft gear. reason i ask is because delaer did the TSB on the timing chain noise and they where suppose to replace it, which i think they did. but hte noise came back last week

 

Between 185 and 145 with a difference of no more than 15.

Yes. In this picture:



If you look below the camshaft gears on the left, you'll see where the chain arc's inwards between the cam gear and the crank shaft gear? That's the tensioner. Its about 8" long or so.

 

THANK YOU for the pics..it helps to have an idea of what I may be seeing in the future

 

How many miles were on this motor? It's good to see the hatch marks still plainly visible in all of the bores. That block is in excellent shape

 

No need for a built motor, however since you now have an extra set of heads + cams. I suggest getting the heads ported and getting the cams reground. You'd be surprised by how much power you can get after the heads are ported and running more agressive camshaft grinds.

 

87k miles, with lots of trips to the track, a few bottles of nitrous and boost for about 4k miles.

That's more what I ment. I'm also interested in a project like MardiGrasMax, but I haven't looked into either, as I'm not going to do anything anytime soon.

 

87k and it still has the cross hatch markings on it? damn.

can you measure the taper?


I cant remember exact specs, but the VE engine I tore down with 165k has 1/5th the cylinder taper as my Mustang, with 49k

 

Some Jap mottors still have cross hatches at 200k miles. 87k miles is nothing thats why the marks are brightly visible. And I doubt he has a dial bore gauge to measure the taper.

 

No, I don't. Always could pick one up though (perhaps rent one?).

 

Cool sock puppet.

 

Nice work Ejj. I been pricing engines and our VQ engines are not that expensive, start about $400 for a complete engine which is a great price. I may purchase one next year rip my current engine off and look for a 2k2 block and figure out how to do all that stuff you guys are doing and see how can I drop my compression.

 

thanks for the pictures, now i can tell someone what the inside looks like :-D

 

Can't you use thicker head gasket to lower compression?

 

That should definitely do the trick.

 

Thicker head gaskets on a OHC motor will retard the cam timing. That is the cheap way out. Anyone who has the motor apart and wants to lower compression needs to do the job correctly and get the correct pistons or remove material from the bowls.

 

Why would it retard the timing?

 

Actually I goofed. Milling the heads would retard the timing. Adding a thicker head gasket would advance the cam timing.


Look at the picture at the top with the cam gears and see if you can figure it out.























If the cam is lifted up or moved further away from the crankshaft the cam is rolled forward.

Also, on a V block the cams will be moved further apart form each other and that will offset the cam timing bewteen banks. The rear bank will have a larger degree of change than the front bank. And on a VQ you really can't use thicker gaskets because the front cover wont line up correctly with the cylinder heads and cam centerlines.

 

Yeah...I see it now. Wouldn't 1 set cams get advanced, but the other get retarded?

 

NO.


Notice the tensioner on the left side of the picture.

 

I don't see how those gears won't need to turn slightly in opposite directions to make up the difference.

 

holy detonation batman!!

maybe im just seeing things, but to me it looks as if half your pistons went on vaction without any lugage

 

its just carbon his pistons havent had a vacation yet.

 

What makes you say that? The carbon build-up?

 

Because that's all it is. Gasoline aka: Hydrocarbons. That black soot in the exhaust manifold = carbon. etc. etc.


soot ( P ) Pronunciation Key (st, st)
n.
The fine black particles, chiefly composed of carbon, produced by incomplete combustion of coal, oil, wood, or other fuels.

 

to me in the pic it looks as if half your piston on the top side is gone. but then again, pics are deceiving.

i'll go back to my hole now

 

LOL, all the pistios are there.