1989 L98 Head Gasket Replacement

[TedC]

When changing head gaskets on a 1989 L98 (aluminum heads), can you just unbolt the heads with the complete valve trains in place, remove old gaskets, install new gaskets, and torque the heads back down? The reason I ask is that the steps I've read talk about lash adjustment. Just not sure if the installed valve trains mess up the proper torqing of the heads on reinstall. If you can keep the valve trains inplace, can valve seals be replaced without removing rocker arms and getting into lash adjustments? Thanks in advance. I'm scoping out a winter project, and trying to avoid getting involved in too much engine internals. Thanks in advance.

 

[Rex S]

OK Ted, your post shows you to be kinda new to this While it is not a hard job, I sugest you read up on the project and have a knowlageable friend with experiance help or at least watch over your sholder and guide you. The valve adjustment procedure will be listed in a manual which is a must have item. Valve seals require the removal of the valve springs and that requires special tools. A good set of tools along with a torque wrench will also be required. Please understand I'm not trying to talk you out of learning but you must get into this with your eyes open.

What prompts the head gasket replacement? Coolant leak or some one else's idea of what is wrong?

 

[TedC]

Rex, Looking at replacing fuel injectors while I'm in replacing the intake gasket (source of rear oil leak). Based on other posts, it appeared that head gaskets on L98s are good for about 20 years. Was hoping I could disconnect the exhaust, unbolt the heads, install new gasket, and bolt the head back on. I have the 89 service manual, and my desire is to avoid any valve adjustments. 400 CI Mopar was the last time I played around with head gaskets, and all I had to do was remove a straight rocker arm bar that held all the valve rockers in place. No adjustments required, but the rocker bar was installed after the head was tightened down to spec. I appreciate the feedback.

 

[vetteoz]

Was hoping I could disconnect the exhaust, unbolt the heads, install new gasket, and bolt the head back on.

You could but a PITA to line up 8 pushrods with rockers while trying to seat head
Would be advisible to reset valves .

 

[gmjunkie]

You could but a PITA to line up 8 pushrods with rockers while trying to seat head
Would be advisible to reset valves .

And then,You'd end up with something Phalked Up!!hnoeshnoeshnoes
It never fails,trying to do something "The so called easy way and cut corners" ends up Phalked Up!!

 

[John Robinson]

How about this

When you have the heads off it is a perfect time to take them to a machine shop and have the valves redone and the head checked for flatness and milled if necessary. While they are there they could go ahead and replace the valve seals and knurl the guides if they are worn. On the other hand you could just leave well enough alone and not disturb them and just do the intake manifold to fix the leak you have there. I guess the real question is how many miles are on the car. And what are your future plans for the car. If it is a low mileage car less then 100K then the pistons and rings etc. are probably good which would justify doing only the intake to correct its leak. However if it is a high mileage car over 175K then you probable should consider doing the whole engine especially if you plan to keep the car and use it as a daily driver.

 

[TedC]

OK OK I got the message. With only 60K, I'll focus in on the intake oil leak and replacing the fuel injectors with the Bosch III from FIC while I have everything apart. I'll save the new Santa tools for another project. Thanks for keeping me out of trouble.

 

[John Robinson]

OK OK I got the message. With only 60K, I'll focus in on the intake oil leak and replacing the fuel injectors with the Bosch III from FIC while I have everything apart. I'll save the new Santa tools for another project. Thanks for keeping me out of trouble.

What kind of Santa tools did he bring you?

I have had the intake manifold off my car a couple of times last year if I can be of any help contact me.

 

[TedC]

1/2" stuff. I'm now ready for knuckle busting projects. Replaced the EGR this past summer and was one step away from pulling the intake. I plan on using the "right stuff" to seal it up tight. Hoping to find time to complete this project during the winter. Prefer to be driving and waxing the vette come Spring.

 

[TedC]

Just ordered the Bosch III injectors and install kit from FIC. On the intake manifold, was planning on using Fel Pro gaskets and the "Right Stuff" unless anyone has a better recommendation.

 

[G Winter]

Be sure to have ALL OIL off the surfaces you use the Right Stuff on. Even a drop of oil will cause a leak. I think brake cleaner should work to clean off the oil.

Glenn

 

[SPANISHVETTS]

Be sure to have ALL OIL off the surfaces you use the Right Stuff on. Even a drop of oil will cause a leak. I think brake cleaner should work to clean off the oil.

Glenn

Why the new injectors?

The intake leak is to be expected BUT are you leaking just a bit of oil or is some coolant disappearing? There is not not much metal around the back of the rear Rt hand cylinder and the different metals would be happy to react if anybody put tap water into the radiator one day during the last 20+ years.

I have seen several L98 heads with corrosion just under the gasket on the back cylinder.

 

[TedC]

Spanishvetts, I've wanted to fix the intake leak and polish up the intake manifold, runners, and plenum to look like new since I purchased this vette 3 years ago. The coils in Multec injectors are exposed to fuel for cooling purposes and today's fuel with higher amounts of alcohol eat away at the protective wire coating causing shorts. They are working fine, and post proper ohms, but while I have the manifold off is the right time for me to replace them. The Bosch III injectors are top rated replacements, cost effective at $170 for 8, excellent spray pattern, no exposed coils, and designed for today's fuel.

 

[joshwilson3]

Spanishvetts, I've wanted to fix the intake leak and polish up the intake manifold, runners, and plenum to look like new since I purchased this vette 3 years ago. The coils in Multec injectors are exposed to fuel for cooling purposes and today's fuel with higher amounts of alcohol eat away at the protective wire coating causing shorts. They are working fine, and post proper ohms, but while I have the manifold off is the right time for me to replace them. The Bosch III injectors are top rated replacements, cost effective at $170 for 8, excellent spray pattern, no exposed coils, and designed for today's fuel.

Might as well replace them if you don't care to spend the money on them while you have everything apart. The Multecs would probably give you problems at some point anyways.

 

[TedC]

I'm not a fan of replacing parts when they work. Multecs had great advantages over other designs when they first game out, but they don't age well, and have a history of issues even if they post proper resistance. Warm front moved in (32+ degrees), so if the injectors arrive on time, I'll tackle this job over the weekend.

 

[TedC]

Quick update...

The oil leak was caused by a loose manifold bolt. Torqued it down without replacing manifold gaskets then installed the Bosch III injectors. So far no leaks. I was surprised how dirty the inside of the plenum and runners looked. Carb cleaner worked great. With Bosch III injectors, you do not reuse the rail clips, so the injectors can be replaced now without taking apart the intake. I primed the rail a few times with ignition on and a pressure gauge that has a relief valve to purge any air. Great way to checking for leaks before proceeding. Engine started right up with a very smooth fast idle and idle. Come spring when I get the vette back on the road I'll report back on any real improvements. Based on positive comments from others, I'm expecting some improvement in MPG and power due to the improved fuel atomization.

 

[joshwilson3]

Quick update...

The oil leak was caused by a loose manifold bolt. Torqued it down without replacing manifold gaskets then installed the Bosch III injectors. So far no leaks. I was surprised how dirty the inside of the plenum and runners looked. Carb cleaner worked great. With Bosch III injectors, you do not reuse the rail clips, so the injectors can be replaced now without taking apart the intake. I primed the rail a few times with ignition on and a pressure gauge that has a relief valve to purge any air. Great way to checking for leaks before proceeding. Engine started right up with a very smooth fast idle and idle. Come spring when I get the vette back on the road I'll report back on any real improvements. Based on positive comments from others, I'm expecting some improvement in MPG and power due to the improved fuel atomization.

I've never heard that with the Bosch III that you don't have to take the intake apart to remove them. What is it you don't have to take off compared to if it had Multecs? On my 89, the PO put in Accell injectors.

 

[TedC]

The Multecs use a rail clip that you rotate to remove the injector. These clips are visable once you have the rail out and upside down. So stock style injectors are mounted first into the rail (locked with clips), then installed in the manifold. With the Bosch III, you mount the injectors in the manifold first, then press in the assembled fuel rail with no clips. My guess here is that GM wanted to install the injectors and rail as one assembly, locked together with clips at the plant. It does take a little more care and time to set in the rail when you install the injectors into the manifold first so you don't mess up the o-rings. FIC recommends using liquid soap on the o-rings (not oil) which does indeed make installation easy. So the real question here is did they use the clips when they installed your injectors? The Multec is too long to remove this way even if there was no clip.

 

[joshwilson3]

The Multecs use a rail clip that you rotate to remove the injector. These clips are visable once you have the rail out and upside down. So stock style injectors are mounted first into the rail (locked with clips), then installed in the manifold. With the Bosch III, you mount the injectors in the manifold first, then press in the assembled fuel rail with no clips. My guess here is that GM wanted to install the injectors and rail as one assembly, locked together with clips at the plant. It does take a little more care and time to set in the rail when you install the injectors into the manifold first so you don't mess up the o-rings. FIC recommends using liquid soap on the o-rings (not oil) which does indeed make installation easy. So the real question here is did they use the clips when they installed your injectors? The Multec is too long to remove this way even if there was no clip.

I don't know. The Accel's were already on the car. I have heard of others using the clips when they replaced the injectors. But I guess if the Bosch III's don't need them, then you can do without.

Wouldn't you still have to take the plenum and runners off so you could lift the rails out of the way to remove the Bosch III injectors?

 

[TedC]

No. Bosch IIIs are both shorter and thinner than Multecs, so there is just enough room between the runners and plenum to lift the rail up enough for Bosch IIIs.