OK, looks like I've got a leak on the rear of the intake gasket on my stock L98, 89 coupe. I'm planning to replace all my coolant hoses and when I do that I'll do the intake as well.

I'm not looking to really mod the engine but I wouldn't reject advice of simple low cost changes while I had the intake off.

So, I know for sure I'm doing this
Replace coolant hoses - all
remove intake to replace gasket
swap thermostat since I'm right there
cleaning of TB & intake, it needs it.

What should I be ready for on this job?
Any recommendation on intake gaskets?
Do's/Don'ts
Small general maintenance or upgrades?
Special tools?

Thanks, first time to crack open the L98.

 

Buy this intake gasket kit from Summit http://store.summitracing.com/partde...8&autoview=sku and only use the "Right Stuff" sealant by Permatex, on the ends of the intake manifold.

You could also, port the intake base if you have time or buy one already ported like this http://store.summitracing.com/partde...5&autoview=sku

Also, you should replace the stock Mutec fuel injectors with the Bosch III's from Jon at http://fuelinjectorconnection.com/sh...&productId=134.

Also, use a good quality #40 torx bit since there are a lot of bolts to remove and put back. Torque the Intake Manifold torx bolts to 35ft. lbs. and the Runner bolts to 25ft. lbs.

 

Use Permatex "The Right Stuff" gasket maker for the front and rear of the intake, making sure to go up onto the heads a little on each side. You must work fast with this stuff though. However, there is no need to be worried about letting it set overnight and blowing out the RTV like with other materials.

Use copper rtv, smeared with your finger, around the coolant ports of the heads and do it also on the top of the gaskets. Buy the Fel-Pro TPI gasket kit from AutoZone. It will include the intake gaskets, EGR gaskets, fuel rail o-rings, etc. Open up a rewards card at AutoZone if you haven't already.

Buy a very good torx bit for the intake/head bolts. I broke the 4 corner bolts and spent a month digging out the extractors that snapped inside them. Change out your intake bolts to grade 8 hex heads (they are SAE threads!!!) or use a die on your old bolts if you didn't snap them or strip them a bit. Before you remove the intake-cylinder head bolts, use some sort of penetrating fluid, like PB blaster, or better yet, Kroil. Be very careful with these bolts, they are steel bolts in aluminum. I heli-coiled the 4 corner bolts and ended up heli-coiling the rest of the intake bolts as well. The heli-coil is a stainless steel spring/thread insert that will be much stronger than the soft aluminum.

Install a new water pump while you're there.

Put ANTI-SIEZE ON EVERY BOLT!! The only ones without antisieze should be those that go into the coolant ports, and these should have some Permatex silicone thread sealer (available at NAPA).

Use a center punch and 'dimple' the rear and front china walls (front and rear of the intake), and the underside of the intake manifold. This will give some texture for the gasket maker to grab onto.

Label EVERY SINGLE BOLT!!! The plenum-runner bolts (T-40 or T-35) are all different lengths!! I took a piece of cardboard, made a bolt schematic, and then punched a hole for each bolt with a #2 phillips. Then you just put each bolt in the cardboard as you remove them. In addition to this, take pictures with your digital camera. If you'd like, I can post a how-to thread later tonight with some of the hundreds (literally) of pictures I have from when I did it.

Buy a Lisle Razor Blade Scraper from SEARS. It's worth its weight in gold for removing old gasket material.

When you have all the intake bolts removed, you can stick a pipe into a runner and pry upwards. Do this on both sides and you'll hear the intake seal break. You can also use a pry bar to pop the injectors/fuel rail out of the manifold.

If I think of anything else, I'll post.

-Jonathan

 

+1 on "The Right Stuff"

+1 on getting a nice long Torx bit. I got a "Snap-On" bit that is about 10" long. Very useful for getting to the rear inner runner bolt on the driver's side.

+ 1 on replaceing the injectors. The Multec's do not have a good reputation, and if you are already going to be pulling the manifold, then I would spend the money.

I also recommend a tap and die set to chase all the threads.

Here is a link to the photo doc I made when I swapped out my intake. Adding aftermarket parts made things more difficult, but it will give you an idea of what is involved.

http://members.***.net/effergyvette/...e_install.html

 

Seeing as how you're in Hotlanta, might as well do a throttle body coolant bypass while you're doing all that.

 

are you guys saying that the black rtv sealeant included in the felpro kit should not be used? I am just wanting some clarification

 

Lots of good suggestions. When I did mine, I replaced the water pump, hoses, thermostat and some other odds and ends. Looks like I'll be pulling most of it apart again, to do the injectors this spring. Should be much easier this time, and I'm replacing the torx stuff with the ARP kit I bought. Still need the runner to plenum bolts though...

 

If you have problems getting the intake to break loose there is a little place on the front that sticks out and is made to pry on , put a block of wood down and pry against it...WW

 

If you bought the ARP Stainless Steel hex kit off of summitracing.com, the bolts are too short. I still need to return mine, it's been about 3 months now.

-Jonathan

 

Correct, do not use that. Plus, the little tube that comes with it doesn't look like it has enough in it. Lay a pretty thick line on the back and front - it should look a little thicker than the cheese-in-a-bottle width. Just cut the nozzle appropriately with a razor.

 

If you use the RTV silicone, you should let it sit 24 hours prior to use. Use the RIGHT STUFF and there is no waiting.

Dimple the "china walls" with a center punch....

Label everything that you pull off, including each bolt. The bolts that hold the runners to the intake are different sizes.....label them so you get them back where they belong. Same with hoses and wires....label.....label....take pictures....or make drawings....you will thank us later.

 

chesse in a bottle, aka spray chesse

 

Valve seals ???

 

It is very tempting to pull the heads at this point and get these worked but I think I'll pass on this as this car is more of a cruiser now with us have the 04 Z06 for solo/track days.

It get's very tough to draw the line!

All the ideas here are great, I need to start getting my parts and then get started.

 

amen

 

when you get the manifold off, put some heavy duty shop towels or rags into the port holes, so when your scraping the old gasket off it won't fall in there. Mark the distributor with a slash and a slash on the manifold itself to match up on reassembly. (kinda critical)

 

good advise. I couldnt believe the crud on my engine. I found an acorn no joke

 

The Runner to Plenum bolts get torqued to 25 ft. lbs.

 

Hi,

This isn't my thread but I am in the middle of the same project on my 87. I have successfully removed the plenum, runners, and fuel rails, haven't gotton to the intake itself yet but I have tons of questions which I hope you guys can assist with.

1. Anyone have vacuum line diagrams for an 87 or similar years? I marked them as best I could but engine degreaser and sharpies don't get along, plus they are brittle little suckers which keep snapping and I find them loose and don't know from whence they came.

2. How can I tell if I have stock injectors on my car? Mine are all black with no obvious markings on them. I really cannot afford to replace them right now, car seemed to run okay when I started this project. But if they are 22 years old it might be time to replace them. (Ohm tested per video, all eight at 15)

3. The runners connecting at the front passenger bottom of the intake and drivers side rear bottom of the intake both have burnt residue on the gasket faces? Is this an indication of a problem like valves or anything else of importance?

4. My thermostat is seized into the intake so I am going to dig it out and replace it, given I live in Florida would a 160 degree thermostat make sense?

My apologies for being such a shade tree type but this job is a lot larger than I thought is would be so Thank you in advance to everyone who responds with advice.

Happy motoring,
Phil

 

160* stat will be fine. My injectors are quite old(oringinal as well). Unless they are leaking, they should be fine. If you run a bottle of Techron Chevron fuel cleaner thru your gas tank, that would clean out any gunk. You shouldn't replace them unless they are causeing problems. There is a vendor on here who sells injectors for a good deal. You should contact him if your injectors do fail, or you decide to replace them before then. As long as you don't have the multecs you are in good shape! If your vacum lines are snapping, you should probably replace them with new ones from NAPA auto parts. Sorry but I do not have a diagram for them. What do you mean by "burn residue"? Oil, road grime, or burned gasket? My engine had lots of black burned on gunk all thru the engine bay and especially under the plenum and around the runners. Simple green will clean it off and not damage any parts.