Crank seems to be seized... taking engine apart.

[Nissan420z]

Hi, my name is James and I am new to this forum. I just have basic knowledge about servicing and repairing cars, but at least I have a service manual and internet to help guide me.

I have this 300zx that has been sitting for a long time and I think the crank is seized. Also the gasket may be blown because there's water mixed in with oil. I think the pistons are stuck on the cylinder walls and I can't seem to break it loose. What would be the best way to get it cranking? Should pouring in some penetrating oil through the spark plug hole help free the pistons up? I am trying to remove the head so I can see the damages and try to rebuild it. I am trying to set cylinder 1 to TDC before removing timing belt. Any advice or opinions is much appreciated. Thanks.

[PapaSmurf2k3]

Yeah it definitely sounds like your head gasket is gone if you've got oil and coolant mixing.

I'd probably start by removing all plugs, spraying penetrating oil down the bores (and letting it soak for a little while), shifting into neutral, and putting a big ratchet/breaker bar on the crank pulley and turning it over by hand.

[NolimitZ32]

If your engine has had water sitting in the cylinders for prolonged periods of time it may not be salvagable. what are your plans for the engine if you do end up getting it to turn?

[Nissan420z]

Well, I would like to pull out the head so I can see how bad it is. If it does turn, I would want to rebuild it if it's salvageable.
I found this while searching. Do you think using coke is a good idea or should I just stick with either WD-40, PB Blaster, or that Marvel Mystery Oil?

After trying the aforementioned soaking to no avail, determine which cylinder is on the compression stroke by removing the spark plugs and using a compression gauge hose or other hose that fits snugly in the spark plug hole. Blow in the hose, if you can't easily then you have the one on compression stroke (if you use a gauge hose make sure it has no Schrader valve in it). Break the porcelain out of an old spark plug and thread the metal body for a large grease fitting (1/4" NPT). Insert the plug in the cylinder that's on the compression stroke and pump it full of grease using a grease gun filled with cheap light weight grease (like white grease). Grease guns can develop thousands of pounds of pressure with no impact. Once the motor breaks free you can rotate the motor to squeeze most of the grease out of the spark plug hole.
Another approach is to put an ounce of Marvel Mystery Oil, WD-40 or PB Blaster into each cylinder and then pressurize with compressed air. On cylinders that are not under compression, the compressed air will distribute the penetrating oil. With the cylinder under compression, the compressed air will act to rotate the engine while driving the penetrating oil past the rings.
I tried all of the above and was about to give up when a "old timer" told me about using Coke a Cola, I didn't believe it but why not try it. I poured a can of straight red can Coke in each spark plug hole. Let sit overnight. Next day I pulled on the breaker bar and with hardly any pressure it rotated free and easy. Ever see what coke does to a penny soaked over night?
Coke works because it's acidic but I don't care for the sugar it leaves behind; we use various oils. We spray an ounce of Mystery oil in each hole. Then we come back with a long angled blow nozzle with good pressure. Not to turn the engine over but to cause the oil to coat the whole cylinder. A small percentage of liquid mag wheel cleaner will mix with the red oil.
Use good eye protection. Blow all the cylinders to coat the whole inside. Give it a couple days or more so it can dissolve the rust. No telling how much might be in there. Go back after you've waited as long as you can. Screw in the adapter charge each cylinder with fifty or so psi. It helps if you completely loosen the rockers first so any cylinder you charge has the valves closed. If it doesn't turn over at fifty psi it's not ready. Apply more oil and wait as long as you can. It's a bit of work, but if the object is to SAVE the engine and not just prove you can turn it over, you have a 90% chance of saving what is left of it.

[Nissan420z]

Ok can anyone help me out with removing the intake manifold and I'm not talking about the upper plenum. It looks like the back of the intake manifold is connected to the EGR? Correct me if I'm wrong. There are these 2 curved pipes blocking the EGR. I managed to get the left or driver side one out but the other one I am not sure how to remove it. I see 2 bolts where the EGR is but they are too hard to get to or no space to get the bolts out because of that curved pipe.

[J30tChumpCar]

Honestly just use this motor as practice, it is going to be garbage from sitting with a mix of oil/water everywhere. Everything you need to reuse in the rebuild (think camshafts) will have rust, you will spend double trying to rescue something that has not only the rust but prior to that had been compromised with heat (think about valve seats in 30,000 miles)

[Nissan420z]

Honestly just use this motor as practice, it is going to be garbage from sitting with a mix of oil/water everywhere. Everything you need to reuse in the rebuild (think camshafts) will have rust, you will spend double trying to rescue something that has not only the rust but prior to that had been compromised with heat (think about valve seats in 30,000 miles)

That's what it is. I'm just doing this as a hobby. I would still like to take the engine apart so that I can learn about it. I just want to remove the heads so I can see the damages. Once I figure out how to remove that intake manifold then I can work on taking the heads out.

[NolimitZ32]

If you have the upper plenum off yu should be able to unbolt the EGR inlet pipe from the DS (IIRC) manifold and the lowwer planum should come off with the EGR and all lines still attached. The actual EGR body is bolted by (Once again IIRC) 4 bolts to the back of the lower plenum.

[Nissan420z]

If you have the upper plenum off yu should be able to unbolt the EGR inlet pipe from the DS (IIRC) manifold and the lowwer planum should come off with the EGR and all lines still attached. The actual EGR body is bolted by (Once again IIRC) 4 bolts to the back of the lower plenum.

Finally got the lower plenum off, but it did not come off with the EGR and all the lines still attached. I also had to remove the back timing belt plate in order to pull it out. Now I can work on getting the heads off. The service manual doesn't really help much. It just says take off this and take off that but doesn't tell you how to do it. Any tips or instructions on removing the heads is much appreciated, otherwise I'll just try to figure it out. Thanks.

[NolimitZ32]

Its pretty obvious if you take the time to look that the rear timing cover needs to come off, granted the first time I took mine apart I ended up bending the isht out of it instead of doing it properly but I guess you live and learn. So are you saying the EGR is still in the car but the lower plenum is out?

[Nissan420z]

Its pretty obvious if you take the time to look that the rear timing cover needs to come off, granted the first time I took mine apart I ended up bending the isht out of it instead of doing it properly but I guess you live and learn. So are you saying the EGR is still in the car but the lower plenum is out?

I noticed I had to when I looked at it, but it didn't mention anything about it in the manual so I just went ahead and figured out how to remove it by removing the 2 pulleys.

Yeah, there were 2 more bolts behind the EGR that was holding it together to the plenum. I wasn't able to remove it with the EGR because there is a curve metal pipe that's in the way.

I see 2 big a** hex screws next to the spark plug holes which I'm assuming to remove the heads. I can't break that b**** loose and I don't want to break the bolt. Will need to buy another bottle or 2 of PB Blaster tomorrow. There seems to be a lot of space that I can get to now. There's more room to work with and now I'm wondering if I should just pull the engine out. I might have to do it after I remove the heads.

[NolimitZ32]

Yeah thats one of the coolant pipes. you are actually supposed to remove the cam gears to remove the timing cover to remove the lower plenum, its also possible to remove the idler stud if you don't want to meess with the cam gears, but since you are doing a full teardown for the learning experience I think its actually a good idea for you to tear it all apart.

[PapaSmurf2k3]

I'd try all the normal oil types before pouring coke in there, but whatever floats your boat.

I've never torn off a Z32 head, but typically there's more than just 2 bolts holding the head on to the block, unless its some sort of crazy old ford or some crap.

With 240s you really have to pull the cams to get to the bolts.

[J30tChumpCar]

You do not habe to remove the camshafts to get the heads off one of these, just the (8?)allen head bolts, they are all the same.

[t.mcginley.jr]

I see 2 big a** hex screws next to the spark plug holes which I'm assuming to remove the heads. I can't break that b**** loose and I don't want to break the bolt. Will need to buy another bottle or 2 of PB Blaster tomorrow. There seems to be a lot of space that I can get to now. There's more room to work with and now I'm wondering if I should just pull the engine out. I might have to do it after I remove the heads.

WAIT! Those 2 big hex screws are NOT holding the heads on. They are just plugs. You have to take the 4 valve covers off first. Then down inside each head there are eight 10mm hex bolts that need to come off. Once you remove all 8 bolts from each side, there are 2 small 10mm bolts (not hex head, regular bolts) on the outsides of the head that need to be removed. The driver side head has this small bolt in the front corner, and the passenger side head has the small bolt in the outside rear corner. If you look where the head meets the block, you should find them.

Once all of those bolts are removed, you will probably need to hit the heads with a rubber mallet to get them to pop off. Once the heads are off, take the oil pan/oil pickup & pump off, then unbolt each rod cap from the connecting rods. Once removed, you should be able turn the block upside down and tap out the piston (with rod attached) with a hammer and piece of wood (think 1 foot of broom handle). Then you can take the main cap girdle off and remove the crank.

[Nissan420z]

I see 2 big a** hex screws next to the spark plug holes which I'm assuming to remove the heads. I can't break that b**** loose and I don't want to break the bolt. Will need to buy another bottle or 2 of PB Blaster tomorrow. There seems to be a lot of space that I can get to now. There's more room to work with and now I'm wondering if I should just pull the engine out. I might have to do it after I remove the heads.

WAIT! Those 2 big hex screws are NOT holding the heads on. They are just plugs. You have to take the 4 valve covers off first. Then down inside each head there are eight 10mm hex bolts that need to come off. Once you remove all 8 bolts from each side, there are 2 small 10mm bolts (not hex head, regular bolts) on the outsides of the head that need to be removed. The driver side head has this small bolt in the front corner, and the passenger side head has the small bolt in the outside rear corner. If you look where the head meets the block, you should find them.

Once all of those bolts are removed, you will probably need to hit the heads with a rubber mallet to get them to pop off. Once the heads are off, take the oil pan/oil pickup & pump off, then unbolt each rod cap from the connecting rods. Once removed, you should be able turn the block upside down and tap out the piston (with rod attached) with a hammer and piece of wood (think 1 foot of broom handle). Then you can take the main cap girdle off and remove the crank.

Thanks for the heads up. I would've wasted time taking those off if I could get them off because they wouldn't even budge. Back to the engine...

[Nissan420z]

I am working on the left/passenger side head and got 8 bolts out and also the little one on the rear corner. Do I need to remove the power steering oil pump too or that bracket tensioner thingy?

[t.mcginley.jr]

Yeah you can remove all those brackets and such, they just get in the way. Just remember where they go for future reference if you end up putting it back together. It's always good to take pics during a disassembly

[Nissan420z]

I finally got the passenger side head loose. I thought I was superman and try to pull it off myself, but I totally forgot it's still connected to the exhaust manifold. Will have to use a hoist to pull it up tomorrow since it's late. I still have to unbolt the other head. I swear those 10 mm hex bolts are hard to break loose. I broke the hex socket and will have to get another one tomorrow.

Yeah I've been taking pictures, bagging and labeling most of the parts. All the screws I would screw them back in it's original hole once part is removed.

... So I finally got the head out on the passenger side. There was a thin pipe line running from the turbo exhaust manifold area to the body of the car near the test pipe or whatever they are. It was hard to unbolt with limited space but managed to. It's a 17 mm bolt with a hole where the threading is. So glad that's off. One more to go then on to pulling the rest of the block. So far the engine doesn't look too bad. We'll see once everything is off.

[Nissan420z]

I need help taking out the driver side head. I got it loose, but same thing like the passenger side there is a pipe running from near the turbo and running somewhere near the AC pump. I can't seem to trace the line to where it ends. Anyone have an idea?

[PapaSmurf2k3]

EGR tube?

Usually you pull the engine with the heads still attached. That's what the slingers (the hooks for your chains) attach to at the factory. Also your weight balance might get messed up if you pull the engine and trans without the heads on.

[t.mcginley.jr]

You can't see where it goes from underneath the car?

It sounds like the oil return line that goes from under the turbo to the oil pan. If its not that then it's one of the coolant hard lines

[Nissan420z]

You can't see where it goes from underneath the car?

It sounds like the oil return line that goes from under the turbo to the oil pan. If its not that then it's one of the coolant hard lines

I can't really see where it's going, but I managed to get the exhaust manifold off instead so finally the other head is off. Such a relief. Time to take a break, then clean things up and then the block is next. Oh yeah.

[Nissan420z]

I see where that pipe finally went to. I had to remove the tensioner bracket next to the AC pump. There was that same 17 mm bolt that had the hole in it. Just the block left, still has the alternator on it though. Should I pull the block out with the transmission or by itself would be fine?

[PapaSmurf2k3]

At this point, either or...