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1992 Z34 3.4 replacement


ss427

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Hi all,

I am in the process of getting my 92 Z34 5 speed back on the road. The old engine had a knock and I will be replacing it with a perfect running 124,000 mile 3.4 out of a 94 CS vert. I will be lowering the cradle out of the Z with the old engine/trans in order to get everything changed over.

 

The question I have is about things I should replace (gaskets, seals, etc) while I have easy access to the whole engine. The 94 engine has some oil leaks, and I know I will be doing the valve covers and oil pan gasket, but any other recommendations would be great! Also, are there any external differences I should be aware of between the 91-93 engine and this 94 engine? I read somewhere a while back about a cam sensor and a MAF sensor on the 94 engine. I have a new timing belt to put on as I don't know when or if it was ever replaced, but should the timing chain be done too?

 

Thanks in advance for any help with this swap. I look forward to getting this W back on the road!

Steve

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Personally, I would change the gaskets and some of the harder to reach sensors while it's out.

 

Then again, I don't know when to stop, because I took my car off the road almost 4 years ago to replace a camshaft and have progressed into body work and replacing the suspension and gas tank, etc etc at this point... :rolleyes:

 

I don't know of specific differences, other than the fact that '94 has the OBD 1.5 computer..

I'd probably pass on doing the timing chain... it's not a big deal I imagine if you're going to do the timing belt anyway, but there are plenty of 200k+ milers out there with the original chain doing just fine.

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the engine has some minor differences, but will be plug and play. the 94+ engine has two sensors not present on a 91-93 engine, and will simply not be plugged in.

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Honestly I would change the head gaskets if I were you and everything up from that. The amount of miles on that motor is about the time they like to go. Like others have said also get some of the harder to reach sensors. Maybe you should even think about a clutch kit or tranny rebuild kit. My take on this subject is make everything you can new and hopefully nothing will go wrong for as long as you own the car.

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Honestly I would change the head gaskets if I were you and everything up from that. The amount of miles on that motor is about the time they like to go.

 

fwiw: LQ1s with blown head gaskets seem to be very few and far between

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I would consider putting a new timing belt and alternator on the engine. I would also put a new clutch set in the car if the current one is original, or questionable. Being that the car is a 5spd, items like the knock sensor and CPS are much easier to access, and can be changed fairly easily in the vehicle.

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I've done this and it is a lot of work to change the timing chain. Don't do it if you don't have to. There's a tensioner that keeps it tight when it stretches. You will have to cut the chain off, then figure out how to pull the lower sprocket from the crank snout - normal pullers won't fit because it is so close to the block, and the woodruff key can also be very difficult to remove. I had to tap threads into opposing holes in the sprocket and use a steering wheel puller with a custom-made plate steel adapter to get it off.

 

I strongly recommend you do NOT drop the engine on the cradle unless you absolutely have to. You will not be able to put it back in the car that way without removing the steering rack and reinstalling it separately, or removing the engine from the cradle and reinstalling just the cradle from the bottom, reattaching the rack, then reinstalling the powertrain from the top. Been there, done that. It's a lot of extra work rather than to simply pull the radiator and fans, pop the axles and detach the mounts then yank the powertrain out the top. It will clear the master cylinder and ABS module.

 

Really hope the CS vert is wrecked, it'd be a shame to scrap one of those.

 

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Thanks for all the tips. I will try taking the engine out through the top. I didn't think it would fit that way but it's good to hear that it will. I have a new clutch disk to put in, but I won't know the condition of the current clutch until it's out. I also plan to put in a new Delco alternator and new Delco plugs all around. Are there any aftermarket plugs that are better than OEM? Also, is there some sort of plug I can use for the distributor hole to keep the oil from getting out through there? Old engine comes out tomorrow!

 

The CS vert is being parted due to rust. I think the owner is saving the body for some type of project..not sure what though.

Steve

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  • 3 weeks later...

Well Ive been making great progress with the time I have, and the engine is about ready to drop back in, but there is one issue. The alternator/timing cover on a 94 is different from 92, so it uses a different plug. I'm surprised nobody knew about this difference in the previous responses. My question regarding this is what I can do to use the new 94 style alternator I have with the 92 wiring. The 92 plug is different - there are only two wires out of it. The 94 plug has three wires coming out of it. I don't have a 94 FSM, so I don't know where the third wire goes, and whether it needs to be used or if it is just a ground. I would like to splice the 94 plug into the 92 harness if at all possible.

Thanks in advance

Steve

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maybe PM Slick. I know he had a newer engine in his older car, I forget what he had to do to the alternator plug for it to work.

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Well Ive been making great progress with the time I have, and the engine is about ready to drop back in, but there is one issue. The alternator/timing cover on a 94 is different from 92, so it uses a different plug. I'm surprised nobody knew about this difference in the previous responses. My question regarding this is what I can do to use the new 94 style alternator I have with the 92 wiring. The 92 plug is different - there are only two wires out of it. The 94 plug has three wires coming out of it. I don't have a 94 FSM, so I don't know where the third wire goes, and whether it needs to be used or if it is just a ground. I would like to splice the 94 plug into the 92 harness if at all possible.

Thanks in advance

Steve

The timing cover is different because of the crank sensor that the 94+ has at the crank, but I didnt; think this affected the mounting of the alternator.

 

As i was stating I was referring to the engine itself, assuming that you would be re-using the original accessories.

 

I have a 92 and 94 FSM, I could look up the chraging system details.....

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I was planning to use a 92 alternator up until I discovered the difference. I was able to figure out pretty easily the other reason for the revised timing cover design, they really beefed up the thickness of the aluminum where the alternator bolts on. The upper ear on the 92 engine was completely snapped off as it was a thin casting. I'd really appreciate if you could look up the 94 wiring diagram. Also, thanks for the quick response!

Steve

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Well Ive been making great progress with the time I have, and the engine is about ready to drop back in, but there is one issue. The alternator/timing cover on a 94 is different from 92, so it uses a different plug. I'm surprised nobody knew about this difference in the previous responses. My question regarding this is what I can do to use the new 94 style alternator I have with the 92 wiring. The 92 plug is different - there are only two wires out of it. The 94 plug has three wires coming out of it. I don't have a 94 FSM, so I don't know where the third wire goes, and whether it needs to be used or if it is just a ground. I would like to splice the 94 plug into the 92 harness if at all possible.

Thanks in advance

Steve

still looking for an answer... my 94 FSM shows 2 wires, as does my 92 FSM...

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Replied to your PM.

 

For others to read, and info for the forum:

 

Ok, I'm remembering now. The 94+ harness has a 4 pin connector. The 91-93 harness has a 2 pin plug.

 

Now, if I remember correctly, you will take the 2 wires from the 2 pin plug, and use them on the inner two wires on the 4 pin plug (meaning the 2 outside pins on the 4 pin plug will not be used).

 

I am not sure of which way is correct, but I do remember switching them dozens of times until I had the right configuration (I mastered the 3.4 alternator swap :willynilly: :lol:).

 

Here's some other stuff I dug up from the past:

 

http://www.w-body.com/forum/index.php?topic=28815.0

 

http://www.w-body.com/forum/index.php?topic=20546.0

 

http://www.w-body.com/forum/index.php?topic=33625.0

 

I think something like this will work, but now that I'm looking through the posts, it is refreshing my memory a bit.

 

http://shop.speedunlimited.com/Switches-Batteries-Alternators/Alternator-Alternators/Powermaster-160-Alternator-p5326095.html

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still looking for an answer... my 94 FSM shows 2 wires, as does my 92 FSM...

 

but here is what it shows:

 

1992

F = Brown = Hot in Run

L = Brown = to cluster indicator

 

1994

C = Brown = Hot in Run

B = Brown w white strip = to cluster indicator

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still looking for an answer... my 94 FSM shows 2 wires, as does my 92 FSM...

 

but here is what it shows:

 

1992

F = Brown = Hot in Run

L = Brown = to cluster indicator

 

1994

C = Brown = Hot in Run

B = Brown w white strip = to cluster indicator

 

Can you look up the plug in the plug reference section at the back of the manual? I am wondering which pin is C and which is B. It will show a front view of the male plug with the letter for each pin. If I know that I think I will be all set.

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still looking for an answer... my 94 FSM shows 2 wires, as does my 92 FSM...

 

but here is what it shows:

 

1992

F = Brown = Hot in Run

L = Brown = to cluster indicator

 

1994

C = Brown = Hot in Run

B = Brown w white strip = to cluster indicator

 

Can you look up the plug in the plug reference section at the back of the manual? I am wondering which pin is C and which is B. It will show a front view of the male plug with the letter for each pin. If I know that I think I will be all set.

missed this. will check.

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Well I got the car started today :biggrin: It runs excellent, but it is not charging in the wiring configuration I went with. My tester is reading about 8-9 and it should be up around 14. I really need to see which pins are used on a 94 alternator, so if anybody could post a picture of the plug page that would be great, but if not it is no problem as I can check it out tomorrow at the Chevy dealer.

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  • 2 weeks later...

Thought I would post some pictures of the whole process. It was a lot of work, but also a lot of fun!

 

Here it comes

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Victory!!

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Anybody ever seen this type of shift arm? It has a 2-3 lb weight welded onto the end, I guess to make shifts easier. The construction tells me it is definitely factory. Car is a 92, pretty late build.

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Getrag 284 after an hour of degreasing. It was worth the time to work with clean dry parts!

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Donor engine work begins

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I also decided to degrease/repaint the cradle. It sucked, but it looks sweet now!

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Donor engine work finished. It's a Chevy so it got a Chevy orange valve cover.

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New Clutch

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Tranny back on

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Ready to drop in

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Fits like a glove. A very odd shaped glove.

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Ready to cruise. Please excuse the Caddy rims. They will be gone soon!

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Thanks again for everybody's help. I can't wait for my next W project. This site rocks!

Steve

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looks like the old engine was not original to the car either.

 

Neither of my 284s have that crazy little weight on the shift arm, weird...

 

good work!

 

and ya know... those caddy wheels don't look all that bad on it. :saaaa:

 

P.S. If you ever want to sell the AIR pump out of it LMK!!

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looks like the old engine was not original to the car either.

 

Why is that? As far as I can recall, the stamp pad had the serial of my car on it. I would probably sell the AIR pump, as I deleted the manifold plumbing while I had it out. I just need to know whether the computer will still run it okay without it. Do you know? Also, was the AIR system only used on the sticks? I thought I saw a 91 auto with it once.

Steve

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ooooh I should have taken a closer look. I just saw that the AIR lines were gone from the manifolds and assumed that someone swapped in a motor from an automatic car.

 

AIR was only used on stick cars, and it does not matter if its there or not, the computer don't care. Mines missing it and the computer does not care one way or the other.

 

a 91' would have the "brake coolers" a pathetic attempt to cool the front brakes with a small electric pump, there's a reason that was a one year only feature :lol:

 

just so long as the little pump works I am interested, I have 2 bad ones.

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