I've got 2 small external coolant leaks. One at the front of the intake and another at the head gasket in front of #7. So it looks like the heads are going to have to come off. Since I'll have to take them off, it seems to make sense to have a valve job done (needs valve seals anyway).

A couple things I'm concerned with is, what kind of can of worms am I going to open up considering the motor has 187K on it? And what should I look for in a machine shop to make sure they're done right. I haven't gotten any good, local recommendations yet that I felt comfortable with. I'm looking at this more from a stock/repair perspective than performance, but I'd still like to have everything done right and replace what's needed. A rough idea on cost for comparison would be appreciated as well.

Forgot to mention, it's a late '86 with aluminum heads.

 

I'd check the compression and for any blow-by first. If there's any sign the rings or pistons are worn, then doing a valve job would make things worse. If that looks OK, then any competent machine shop can do the heads. It doesn't get much easier than a SBC.

 

Do a search on this subject and you'll get an idea of what it takes. On an L98 TPI motor, it might look easy, but it takes a good amount of elbow grease and forethought to do it right! While the ARP bolts are great for the cylinder heads, stay away from them on the intake manifold. The original torx fasteners are a 'button' style of bolt head with more clearance than a regular octagon bolt. You'll have trouble with the TPI runners interfering with the fit to the air box! Take lotsa pics and don't drop anything in the engine compartment. There are places in a C4 engine compartment that once it goes there, you'll never see that bolt/washer/nut again!

 

Paul, good suggestion. I thought of that but haven't done a compression test yet.

F22 are saying R&R ing the heads needs a lot of research or the valve job itself?

 

Some chance the deck of the block has been grooved by the leak and if you want it to seal, you'll have to deal with that. Sometimes you can shave off a few 1000's; sometimes it means a new (or used) block. You'll also want to make sure the head isn't cracked. That can usually be fixed, but weigh the cost vs. new.

 

The R&R of the heads is what you research carefully. Buy a FSM or Factory Service Manual. It will be indispensible! Buy some colored labels and label everything. Also buy some 3x5 index cards and a permanent marker to bag and tag all the bolts, nuts and minor assemblies that don't go back to their exact spot on removal (some guys can work with a bucket of parts, but I sure can't).

Take lotsa photos during disassembly!!! The intake manifold itself must have a dozen little parts hanging off've it that have to go back on at exactly the same angle. The air and water temp sensors are right next to each other and take the same thread, so you can't mix those up either.

Be patient removing all the stuff. You don't have to unhook the AC, it will lay off to the side complete. Ditto for the throttle cables, electrical harnesses, etc. Might as well do the injectors while you're at it and replace the fuel regulator, as it's underneath the TPI on the rear. Note carefully the routing of the vacuum lines on the TPI, as one of the hard lines runs through the inside of the TPI and exits out the passenger side.

Finally, find a Machine Shop that will hot tank all the dirty parts for you! It doesn't cost much, but man, it'll save you hours and hours of scrubbing hard-baked crap off've brackets, etc, etc. Finally don't be afraid to grind the crap off've the top of the pistons with a wire brush. Vacuum real good after you're done!

If you do it right, it will all go back together again. It's been two years since I did the 87 and it just passed California Smog last week again and still running strong.

 

check head for cracks, quick surface valve job.

With thos miles have the guides checked to make sure they are within spec, dont want a fresh valve job only to find the valve is moving around and beating the new surface up. Guides are cheap, they will probably want to do all of them if 1 or 2 are bad. Plus side is they last a long long time and dont really wear much. Rates will vary, have them blend the valve job into the bowl so your flow isnt hurt...some do some dont. Not doing it can hurt flow by 10-15cfm or more.

 

Not to steal or hi-jack this thread but while you are having a valve job done is there any thing you can do to increase compression? Like going from 9.5 to say 10 or 10.5 without incurring major expense or is it even worth it ? Im thinking having the heads milled.
If you haven’t replaced your injectors check them before the tear down also check the FPR and the EGR .
Also you might consider 1.6 rollers

 

You can mill heads, thinner head gasket etc

 

Thanks that is kind of what i was thinking, about how much could you pick up. What would a half point or a point be worth

 

F22, thanks for all the info. I'm just starting to get my ducks in a row right now but planned on pretty much everything you mentioned. Pictures, hot tanking, having the heads magna fluxed, replacing anything necessary as part of the valve job and I'm assuming new valve springs. I was thinking of sending the injectors out for cleaning unless new ones fit the budget.

I've got shop manuals and have been reading some other threads as well, but any info is always good. The car is still driveable now, but when I do go at it, I want to get it done and not turn it into a project.

 

IF you decide to do a valve job check the "overall" cost first. Things like seals, valve job itself, valve parts (if some valves are bad and need replacement), valve springs, milling heads to true up surfaces, and so on get expensive. It could cost less by buying a set of Patriot Performance heads (I just got 2180's for my 89) and you will have a better casting and all new parts to start with, check it out.

I'm not even going to touch on the "other" issues you may encounter by doing a valve job at 180,000 miles, but a leakdown test would be a good investment before doing anything

 

Actually on aluminum heads they're pressure checked, not magnafluxed.

 

C4Boy, it is a project! I'm mechanically inclined and working evenings and weekends, it still took me almost two months to do. If I had to do it over again, I'd definitely remove the front wheels and rotors! Might have made it faster. I am **** retentive, so I was pretty careful doing it, never having done it before. I had a box for all the bagged parts, tags, etc. Gotta have beer and tunes too. Sounds like a long time, but I got the job done right! It went back together and started! That was the amazing part. I was soooo stoked. Best of luck!

 

I thought about this later on (while laying in bed and looking up at the ceiling...). Change the EGR valve too, while you're at it. With that many miles on it, you don't want to have to pull the complex three piece L98 TPI intake to get to a $40 part!

Also it took so long, because I cleaned everything under the hood or clamshell. Replaced the water pump too, as that's cheap and easy to do.

Finally, research how to adjust the hydraulic lifters on a small block chevy. The FSM has you doing it one way, but the machinist at the shop recommended doing each lifter one by one, as they sit on the base of the cam (the lowest point). You can find this on the internet.

 

Compression test is a good idea.

If the heads/valves are good/reusable figure about ~$600 for head/valve machine work and a new spring kit with all the related goodies.

Think about what your willing to invest in an "old" set of heads before you decide between new or redo.