I'm concerned that the exhaust mani's I have may be cracked. I'd like to know if there is a cheap way to test them to be sure they are not cracked.

I think I have mentioned on here that I discovered one of my exhaust mani studs was broken and I have determined the Cat is very close to through. It has been a while. I have the Y pipe from Rock Auto and just pulled the trigger on a Cat and the kit with the rest of the exhaust in it.I want to be sure the mani's are good before I reinstall them.

Also how does one determine if the rockers etc are OK inside the valve covers. I have a tick when its pulling torque that may be a loose rocker or???? I think I thought at some point that it was a lifter. I'd like to know as I could just put some rebuilt heads on if I have to when I do this job.

 

Yours is a 5.2 if I remember correctly.

I was able to do a visual on my 1988 with the 3.9 (hint: If there's a visible fissure, and you can see light through it, it's cracked ... ) What I've seen some guys do is mix up some bubble water (Dawn 15%, water 85% or so) and spray the manifolds cold; then fire the motor up (you want to use this BEFORE the manifold gets hot enough to steam the water off ...) That'll blow bubbles where it's leaking.

Or, you know, pull'em and look at'em. That won't find the hairline cracks, though.

As to how to determine if the rockers are OK - pull the valve covers, and do a visual exam, and check the valve lash using the instructions in the factory service manual.

RwP

 

Thanks Ralph I have the 94 3.9. That Dawn/water idea sounds like it would work. I just want to have everything ready to do in one go before I start taking it apart. I don't want to have to wait for new parts. Looks like I have to do some reading. :/

 

Well - I am NOT happy with the replacement ATP I bought for my 1988 after I found that hole in the original.

The heat riser counterweight clip broke, the counterweight shaft fell out of the manifold while I was driving, the exhaust was aimed right at the starter motor, and I never did find the butterfly plate ... so I'm betting it's jammed into my Y-pipe right now. Grumbles.

I picked up a good set of original Mopar manifolds at the boneyard for $30.

If you go that route, try to find a 1992/1993 manifold set - they were a small bit larger, took a bit larger Y pipe, but allowed the motor to breathe a bit better. (That may only be for the 5.2, though ... still, if you have to grab a set ... also, have them media blasted and coated to be gorgeous when you assemble *grins* )

RwP

 

Thanks again. Still have the 3.9 though I was told I could get some 93's for $75 by my local recycler. I already have the new Y pipe for the 94 got it all from Rock Auto. Honestly as much as this thing improved by me fixing the intake plenum I'll be happy with the stock option. Aside from the wasted money on the tranny this is costing me right around what I figured to make sure it gets another 140K. If the head checks out and the exhaust/mani has the effect I expect all I'll need to do is install new rubber Sheesh I can't even think of the right term. The front end replaceable bits. My first fix was new front rotors, bearings and calipers.

 

I have a 93 vette. I installed long tube headers and needed to tie the orig. exhaust into the header collectors. Well to say my welding abilities are lacking would be an understatement!! Anyways, to check my welds and connections, I took the hose from my shop vac and put it on the exhaust side. Then connected that to the tailpipe. Turned it on and use a bubble solution to look for leaks. It actually works well. I would think it would work for the exhaust manifolds too.
FWIW I used a solution called big blu. We use it for checking Freon leaks, but again, any sudsy soap solution should work.

 

Well Ralph I tried it and the stuff bubbled up right next to where the stud broke. It seems like it was very hot on the driver side closest to the firewall. the stuff foamed up so much I couldn't tell if it was a leak or the heat. I had just started it and sprayed the passenger side first. Seem weird to get that hot so fast. I may try that side first tomorrow morning to see if it does anything right after it starts. Ragged I might try that after I put the new pipes on. I'll have to remember to dump the garbage out of the vac first though

 

Uhhh ... no. Foam it, and have a friend start it while you're watching.

You want those manis COLD.

RwP

 

New Data

Today I sprayed it on the driver side with the soapy water cold and it showed a leak at the gasket for the two cylinders on the driver side. It went away pretty quickly.
I proceeded to take the valve cover off and it all looks clean and tight. I could not move anything by hand. I wasn’t really sure what I was looking for when I had the cover off. The FSM says to look for looseness and I started it up and no noise and the oil came up in 30 seconds or so. I wish I could say it was normal but I have no point of reference.
The washers that sit on the springs all had white metal marker on them as if this were a rebuilt head. I had that same idea from the markings I saw in the motor when I did the intake plenum.
I vacuumed up the bits of dry friction tape and retaped the wire harness that runs behind the valve cover. Then when I went to put the valve cover back on I went to tighten the studs where the leak was on the exhaust. One stud was already sheared and the person who did it just put the broken piece back into the hole! The other stud nut was a ¼ inch off the surface of the manifold. I tightened it but not too tight for fear of breaking it.

I am starting to think the lifter or ??? noise I am hearing on that side when I go up hills is due to that manifold not being secure.

I am wondering if this and the other manifold could be warped as it looks like it has been untended a very long time. I checked with my laser thermometer and from start the driver side mani over the two cylinders was up past 200 in less than a minute. In a couple of minutes it was past 370F. IDK if that is normal. The passenger side was that hot too.

The only way I know to be sure any different mani’s I might install are flat across all three cylinders is to get new ones. On Rock Auto the Doorman are $79.99 for the passenger side and $122.99 for the drivers side. Is that about right? That seems strange since the passenger side has more complex casting.

 

OK the CAT and exhaust kit came in. Where do I place the jack stands? I know I have to take the front wheels off and then the wheel well liner. I'm a bit dubious of the Walker Y pipe now that I've looked at the position of the exhaust mani connection closer. I'm thinking I may have to bend it because the Y ends point straight up and the mani points back at an angle.