SL1 SOHC - Post-Head Gasket Replacement Startup Issues

[atrain0007]

I just (sorta)finished doing my first Head Gasket job on a car less than 40 years old. I followed the Haynes Repair Manual as closely as humanly possible but I have had issues trying the initial startup.
Mainly, I cant get the car to start right. The car either:
- stammers a little and lets out a backfire OR
- fires up and jumps to 4000 RPM and sits there pulsing, pulsing, pulsing (it sounds mechanically good, its just racing).

Did I screw up the timing when I put the chain back on? Is there some sort of adjustment I can do from the outside of the engine? I didnt think so but at the end of the Head Installation section, Haynes Repair manual refers you to chapter 5 for timing (and there isnt anything in chapter 5 about timing).

Any help/ideas would be appreciated.

A

[bobfather99]

Time to do a quick check of the easy stuff, before you look at a timing mistake.

All plugs/wires on tight and in the right spot??
Loose vacuum connections??
Clean coil terminals??
Check connections at Fuel injectors??

Id retrace your steps, just to make sure you didnt goof up something small.
Id hate for you to tear into it, only to find out it was something else.

[Squareback]

First things first, why did you replace the head gasket?? Fairly rare for a SOHC car to blow a head gasket. Usually the head cracks.

Regardless, double check and mae sure you have the big vacuum line going from the back of the intake to brake booster hooked up at both ends. That's an enormous vacuum leak that will cause your RPM's to shoot through the roof when you start it.

[atrain0007]

Originally Posted by Squareback

First things first, why did you replace the head gasket?? Fairly rare for a SOHC car to blow a head gasket. Usually the head cracks.

Regardless, double check and mae sure you have the big vacuum line going from the back of the intake to brake booster hooked up at both ends. That's an enormous vacuum leak that will cause your RPM's to shoot through the roof when you start it.

The reason for replacing the head gasket: pretty good oil leak (with some associated coolant loss) that was diagnosed by the local saturn dealer. I was skeptical at first but they said they are seeing a lot of it. On inspection of the gasket, it seemed like some oil was slipping out of the passenger rear side of the block.

My manual doesnt give me any good diagrams of the vacuum system, the only vacuum line that comes to mind is the one that plugs in on top of the throttle body. It breaks off there to something on the fuel injector rail. It plugged into the injector rail, and its (now) plugged into something under the intake and eventually back to the front of the car.The RPMs are still crazy high, did I miss another vacuum line?

[ssicarman]

Brake booster vacuum line. It is on the passenger side of the intake manifold by the power steering pump. The fitting that is goes on points down. Easy enough to miss putting on if the hose has fallen down. Big enough to run the RPM up to the rev limiter.

[madpogue]

There's also the vacuum line to the PCV valve. The VECI label under the hood shows all the vacuum lines. But that's not your only potential vacuum leak source. What year is the car? Did you keep the manifolds on the head for the repair? From your descriptions, it sounds like a '95 or later MPFI car, in which case, a leaking intake manifold gasket will leak vacuum.

(The "pulsing", BTW, is the engine "bouncing" off the 4000-ish RPM rev limiter.)

What procedure did you use to set the valve timing?

[atrain0007]

Thanks for the help so far.

Its a 1997 SOHC SL1. I took the manifolds off (per the haynes manual). So I have had the intake, the fuel injection rail, exhuast manifold, valve cover, everything on the drive belt, timing chain cover, cyllinder head and chain off.

I replaced the timing chain while I was there and followed the Haynes manual for finding TDC and putting the new chain on. Here's how I did it: With the old chain still on, I turned the engine by the crankshaft bolt with a finger over the spark plug hole until I felt air push out. Then I put a drinking straw in the spark plug hole, and watched when it stopped moving up (as I continued to turn the crankshaft clockwise). Haynes said that would give me TDC, and once I took the timing chain cover, I looked like I was right because the mark on the crankshaft was at 12 O'Clock and the dimple on the Cam Sprocket was also at 12 O'clock.

As far as installing the new chain. I put one of the dark links on the dimpled tooth on the Cam and the other dark link at 6 O'clock on the crankshaft.

So unless I'm 180 degrees off, I thought I got it right. What is the least invasive way to check/fix it if I did get the timing wrong.

I am 95% sure that I have ruled out the vacuum system. I was really careful with all the mating surfaces and cleaning them up before installing the new gaskets.e I have also checked on the vacuum hoses, and they look good.

[Dr B]

Again .....the hose going to the power brake booster,connects to a barb between the intake and firewall (back of intake ) is that connected ?
Otherwise , have you installed the P C V valve/hose assembly?
Is there something holding the butterfly open ,in the throttlebody ?
Broken I A C valve ,though i think you'd only hit about 2200 rpm (there) !

[atrain0007]

Got it! The gasket between the throttle body and the intake manifold must have slipped down before I tightened the second bolt.

The only problem now, which I hope is minor, is that some smoke developes after about 30 seconds of running it. I thought it was coming from the exhaust manifold but I took off the oil cap on the valve cover and it looks like its coming from in there. Can I attribute that to burning off some of the chemicals we used to clean the valve cover? The car has oil, but the valve train had been sitting out for a few days without oil.

Worse case scenario is that Im burning up something in the valve train right? I can pop off a couple of bolts and drizzle some on top of the valve train, but Im just not sure what is burning.

How long is too long to just wait and see?

Also, I can run the car with the valve cover off right and see if there's oil coming up from the block?

Thanks again folks, very helpful so far.