advice on Z34 DOHC

[dalejw3]

Hey guys I need your help. I'm looking to buy a 1992 Lumina Z34 but all my friends seem to think that the 3.4 is a piece of crap. Is the 3.4 really a bad motor or should I not worry about it. tell me what you think.

[NOHC_WBody]

If you have the time/skill/money to afford upkeep on a maintinence intensive car, by all means, go for it. It's not a POS, but it DOES demand a level of attention not often found in today's engines.

 

Look at your financial situation,and how much spare time you're willing to give to upkeep & maintinence and think about:

 

Can I afford to have a dealership change a timing belt?(about 350-600 bones, depending on who you take it to-worst case scenario)

Can I afford the labor to replace an alternator? (it's not that far off from the belt)

[Bolt_Crank]

for most jobs.... you can do it at home, if you have the time, my timing belt, when I look at it, if it's bad, I'll be changing.... and it won't be too hard, just time consuming... but yeah, it takes a bit more work than the average engine, personally, I like it better than my brothers 3.1...

 

 

but, if you drive it gently, it'll last a lot longer

[GnatGoSplat]

It is a picky motor, labor costs for almost any work on it is quite high.

I wouldn't buy one if you're the kind of person that loses his temper when the car has a problem - you know, the type that cusses and kicks the car anytime there's something wrong with it. A 3.4 DOHC takes someone with lots of patience and understanding.

 

Do you either:

A) Have lots of money and can shell out lots of money for maintenance and repairs.

or

Have lots of time, skill, and are willing to do all the work yourself, thereby saving lots of money, but spending lots of time underhood.

 

If you fit either scenario, the 3.4 DOHC might be for you. Even scenario B takes lots of patience, because jobs on the DOHC take a lot more time than any of the pushrod motors. It's almost imperative to have backup transportation as many DOHC repairs take several hours.

[dalejw3]

thanks guys. I just happen to love to work on cars and don't really care how long it takes as it seems like most jobs could be finished in a saturday. I think I'll go for it. I may be in for some help from time to time though.

[GnatGoSplat]

Sounds good to me. Once you get all the common problems ironed out, I think the 3.4 DOHC will go awhile without needing anything.

I fixed a ton of the typical 3.4 DOHC common problems and it's been reliable for at least 6-months.

[Bolt_Crank]

speaking of all the common problems... what might they be? since my DOHC is running pretty damn fine, except for the alternator/waterpump grinding noise... I fixed the stalling by re-attaching a vacuum line, and Imma be changing a bad fuel injector soon.... other than that, though.... zero problems.... and, aside from taking the covers off to look at the timing belt, is there any hints in the way the engine runs? or is it just BOOM, gone?

[GnatGoSplat]

Pretty much all 3.4 DOHC's have these problems:

- Alternator

- Oil pump drive O-ring leaks

- Intake manifold gasket leaks

- Cam timing shift

- Timing belt breaks or shreds

- Leaky injectors

 

Some have more serious problems with heads/cams/rods, but I think those are the more abused ones.

 

And although not caused by the engine, 3.4 DOHC cars also tend to have:

- Power steering pressure hose leaks.

- Aux tranny cooler lines leak.

- 4T60-E problems, or HM-284 problems.

[Bolt_Crank]

thanks

 

now I know what to look for

 

 

and the powersteering thing, I think is the way the hose is made, 'cuz my brothers W-Body already had that go on him

[GnatGoSplat]

They must have made 3.4 DOHC hoses differently, because our 88 and 89 2.8 Cutlass's still have their original PS hoses and no leaks. I think one car has 187,000 miles and the other has 198,000.

The 94 is the one that blew the hose, and it only had 120,000 and is also 6yrs newer.

[CPSMonteZ34]

Being a '92, sometimes you might notice that it won't be the engine that may give you trouble, it'll be things like:

 

- Fuel pump will give up if it's ever been run low on fuel numerous times

- Rear caliper brake sliders seize

- Annoying rear-end creak caused by bad jounce bumpers

- Coolant leaks from a solid pipe along the front-right engine bay near the wheel (too close to area where corrosion is likely to occur quickly)

- Weak pot-aluminum door-stalk handles (mounted in the b-pillar)

 

To help with these, keep your gas tank above the half-full mark at all times. Use your e-brake to assist in preventing the brake linkage from seizing (though it is likely to occur anyway eventually). The jounce bumpers just like to give up - but aftermarket replacements have a bit of improvement (hard to tell though as anything new is likely to last a while). The solid coolant pipe is most easily replaced by a section of hot-water heater hose clamped onto both ends where the rusty section is cut away. Open your doors with BOTH hands: one to pull the latch, and the other to pull the door open along the doorframe. Pulling the freakishly heavy door open with the door handles can weaken the handle stalk over time.

 

The engine is nice. I have a 95 and the only things to go wrong with the car after 85k miles would be:

 

- crank positioning sensor (all sensors can give up eventually)

- fuel pump

- lemon transmission (blew at 40k miles for no reason and from no abuse)

- ignition module

- intake gaskets

- electical gremlin with the auxilliary post & fuse box

- ...and the usual battery replacement, brakes, coolant & thermostat, spark plugs and wires (of which are not a fun job).

 

I think the only bad thing to say about the 3.4 DOHC (a.k.a. LQ1 & VIN-X) is that its general maintenance procedures can be a pain in the ass due to the size of the engine in the bay. It's sometimes difficult to do the simplest thing when compared to other engines. ...but, like you say, if you like working on cars, this is the challenge of patience.

 

There's a wealth of knowledge and assistance with everyone through this board. Fire away with your questions before going into a parts replacement party trying to diagnose a problem. This board will save you a lot of money that way.

[Bolt_Crank]

They must have made 3.4 DOHC hoses differently, because our 88 and 89 2.8 Cutlass's still have their original PS hoses and no leaks. I think one car has 187,000 miles and the other has 198,000.

The 94 is the one that blew the hose, and it only had 120,000 and is also 6yrs newer.

 

 

well, my brothers GP is a 91, so maybe it's the same hose?

 

thanks all

[brian89gp]

My PS hose went at 98k or so and trust me you'll know when it happens, gotta refill the fluid once a week, bubbles in the resivour, and the entire back side of the engine gets doused in fluid.

 

As for wether you should buy a 3.4, if you can and are willing to do the work yourself then you should be fine. It isn't really that things go wrong with it, its that they cost so much for a shop to fix. Most 60v6 engines have the same problems, but instead of taking 10 minutes the 3.4 takes 4 hours.

[91GranSport]

Say, I heard it's a pain in the ass to change the spark plugs on these beasts, is that true?

 

Being a '92, sometimes you might notice that it won't be the engine that may give you trouble, it'll be things like:

 

- Fuel pump will give up if it's ever been run low on fuel numerous times

- Rear caliper brake sliders seize

- Annoying rear-end creak caused by bad jounce bumpers

- Coolant leaks from a solid pipe along the front-right engine bay near the wheel (too close to area where corrosion is likely to occur quickly)

- Weak pot-aluminum door-stalk handles (mounted in the b-pillar)

 

To help with these, keep your gas tank above the half-full mark at all times. Use your e-brake to assist in preventing the brake linkage from seizing (though it is likely to occur anyway eventually). The jounce bumpers just like to give up - but aftermarket replacements have a bit of improvement (hard to tell though as anything new is likely to last a while). The solid coolant pipe is most easily replaced by a section of hot-water heater hose clamped onto both ends where the rusty section is cut away. Open your doors with BOTH hands: one to pull the latch, and the other to pull the door open along the doorframe. Pulling the freakishly heavy door open with the door handles can weaken the handle stalk over time.

 

The engine is nice. I have a 95 and the only things to go wrong with the car after 85k miles would be:

 

- crank positioning sensor (all sensors can give up eventually)

- fuel pump

- lemon transmission (blew at 40k miles for no reason and from no abuse)

- ignition module

- intake gaskets

- electical gremlin with the auxilliary post & fuse box

- ...and the usual battery replacement, brakes, coolant & thermostat, spark plugs and wires (of which are not a fun job).

 

I think the only bad thing to say about the 3.4 DOHC (a.k.a. LQ1 & VIN-X) is that its general maintenance procedures can be a pain in the ass due to the size of the engine in the bay. It's sometimes difficult to do the simplest thing when compared to other engines. ...but, like you say, if you like working on cars, this is the challenge of patience.

 

There's a wealth of knowledge and assistance with everyone through this board. Fire away with your questions before going into a parts replacement party trying to diagnose a problem. This board will save you a lot of money that way.

[CPSMonteZ34]

It's all because of how deep against the firewall, and tall the rear bank is being an OHC design; but it depends on how you do it. With more tools it isn't a problem. The fronts are typical with a 12" ratchet extension. The rears can be done easily with a couple of swivel, and shorter extensions to make access and removal more simple. One long extension is only effective if a little room is made - for instance, pulling the hood weather strip or taking the upper dogbone engine mount off and tilting the engine forward.

 

The method described in manuals calls for an elaborate engine tilt procedure meant to expose the plug holes for easier access. The first time I did it, I was told to go to a hill, pull the dogbone mount, set it in gear with the engine off, and let the weight of the car pull the engine forward. I didn't have a hill handy, so I ended up using a come-a-long and ratcheted the engine forward enough until I had room. So, the more tools you have handy, the easier it is.

 

So yeah, it can be a pain in the ass if one isn't sure of the best way to do it. In comparison to most any other vehicle, it could be considered strange - but I've seen worse access to such general maintenance parts.

 

No, the only real pain in the ass on the LQ1 would be the alternator placement. Anything else is merely a few bolts, a belt, and you're done. This one needs just a bit more time, smaller hands, and patience!

[Baddflash]

My 3.1L also reqiures that I tilt the engine forward to get access to anything back there. It is not a difficult procedure, I remove the coolant reservoir, disconnect both upper mounts, then using a pry bar of some sort tilt the motor forward and lock it in place with one of the mounts.(there's an auxillary hole just for that) I know it's stupid that you can't just get at the back of the engine but thats Chev. I have to remove my upper intake just to change the PCV. You'll find a lot of things like that with the Lumina, but you'll also learn to love a lot of stuff to.

[Paul GTP]

In my opinion Spark plugs replacement is very easy, if you have right rachet extensions.

[JS91Z34]

My Z34 hasn't broke down yet.

[bbender85]

My Z34 hasn't broke down yet.

 

you just cursed yourself.

 

 

 

 

 

 

[JS91Z34]

My Z34 hasn't broke down yet.

 

you just cursed yourself.

 

 

 

 

 

 

Someone else said that to me about a year and a half ago. Still no problems.