I finally started my reman 2.8 today after two weeks of hard work, and after a few fixed coolant leaks I let it run for a minute and within 2 minutes the manifolds, heat shield, and Y pipe all started glowing Bright red. It started on the firewall side but soon it was hot enough for the trunk side and Y pipe. I can hear a loud hiss and i think maybe i have a vacuum leak, but after spraying starting fluid around I couldn't find anything concrete. The base of the plenum where the EGR tube meets might possibly be a leak because I "think" I heard the engine rev a tiny bit when I sprayed starting fluid down there, but with that loud of a hiss I would expect a much larger rpm jump.

Does anyone have any ideas on what it could be? I mean I had an egr tube crack on me in the past and the exhaust NEVER glowed red especially not bright red like coals in a fire.

When I started up my 3.4L for the first time, my exhaust got glowing red hot like you described. It wouldn't rev past 1500 rpm. The problem was it wasn't timed right.

You know thats what I as thinking but then we timed as best as I could. I thought it was at 10 degrees, but then when you turn the distributor a little bit it bogs down and the idle gets slower. I am so ready to bang my head on the wall.

You set the timing with the computer in diagnostic mode or whatever with the two ALDL pins shorted out?

My 3.1L did the same thing and the glow went away after a few minutes of correctly setting the timing.

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- Kyle

Fiero Quarter Mile Database
Fiero Image Gallery

exactly what I was going to say. Use that lil black Device you have, plug it in the ALDL, THEN set the timing...

Deff. sounds like timming, if not I know you have nitrous I am assuming you have a A/F guage, is it running very lean?

Sounds like a clogged cat to me.

The loud "hiss" you hear may well be the intake air. Is the intake system completely installed with filter?

Double check the timing, then exhaust if your certain about no vac leaks.

also, what about the vacuume line on the batt side of the plenum, the big one. Is that sealing?

Make sure that all your vacuum hoses are hooked up. I forgot to hook up the one under the upper plenum and had the same problem you have. Another member forgot the tube that went into the throttle body with the same results. Double and tripple check everything.

I did set the timing with the ALDL grounded. I am almost positive all the vacuums are hooked up. John I sealed the large vacuum on the back of the plenum with some rtv and I sprayed starting fluid over there and got no jump in rPM's.

There is a hard metal vac tube that goes into the Bottom of the TB. Its pretty big, did u leave it out??

Gimme a call, I'm home today

I don't think I left anything unhooked up. Its possible I guess. Does anyone have a pic of the vac line Jnco is referring to?

I recently went through your dilema so I feel your pain. Here is what happened to me so I hope this helps you. After having my cradle out and replacing my head gaskets I put everything back together and checked everything two and three times over....I cranked her up and it started right away and just like you I had glowing manifolds after about 2 minutes of running. I checked all vacumm and could not find a leak.. Well I thought my timming was right. But I realized you cant set timming on these 2.8's with out a timing light and without jumping the a and b ports on the aldl to send computer in diagnos mode. Once I did that I was able to get car into the proper timming with a light and noticed my rpms came down. To about 1000 and then no more glow. Keep in mind also that if you have stock 2.8 manifolds they will glow at high rpms. So if your idle is around 900 to 1100 and your are still glowing then your timming is way off. Vacumm leaks will cause the rpms to be high and thats why you will see them glowing. Anyway sorry about the long post but I hope this helps you.

If you can't find anything disconnected, you didn't seal something right. The lower intake valley comes to mind, it has a 1/8" gap between it and the block and requires a bead of rtv to seal in the front and back. There is a vacuum line connection under the plenum near where the vacuum line for the EGR is. That is the one I forgot to hook up on my last engine when I first started it.

I had that problem after i did the engine work to my 2.8, EGR leaked

Is your idle higher than normal? If you do have a vacuum leak than it will be

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+ a silver 85 2M4 and a gold 87 2M4
--Adam--
IM AOL: FieroGT5speed

Thanks guys I will go everything agan tomorrow and see if I can't get it timed correctly. I do have a timing light to use and it was actually my Father who was having a hard time timing it. I hooked up the ALDL and I am certain we were at 10 degrees. So I think my idle is high from a vacuum leak. I'll tighten the EGR and see if that helps. I'l check the vacuum line you are talking about John. And BTW I did seal the lower intake using RTV on the ends, and I also used a tine layer of it on all the gaskets in the manifold. I torqued them to spec as well.

If the engine will idle with your hand over the throttle body opening, then for sure you have a leak somewhere.

JazzMan

The results are in..... Jncomutt was right on the money. He mentioned there was a vacuum line on the bottom of the TB and i completely missed it evern after going over everything with a fine toothed comb. I sealed it up and started the car set the timing and that was that.

On a side note, just FYI. While I was timing the engine I was still getting a slight vacuum leak and having abot of trouble timing the engine. i got it the best I could and then tightened the distributor the rest of the way down. Thats when I noticed the timing readjust a little and I stopped hearing that vacuum sucking sound. As it turns out the distributor being slightly loose for timing purposes was actually creating vacuum. Air was being sucked into the engine via the dist hole. I couldn't believe it, but now it all works perfectly.
Thanks for the help guys...