Astra Z18XE intake manifold leaks

franc123, Jul 31, 6:41pm
Anyone had issues with the manifold seals leaking! Got one where I suspect this is happening but can't prove it with the usual tests, has got a real rough idle and running very lean,cheers.
mugenb20b, Jul 31, 6:47pm
I haven't come across one yet. O2 sensor fault maybe! TK head check!
wimwom, Jul 31, 6:50pm
Had similar with a x16 XEL engine, it was a very small hole in therubber pipe between the manifolds causing the issue.
thejazzpianoma, Jul 31, 6:53pm
The 2.0 one is famous for vacuum leaks from the hoses which are a bit hard to see, you sort of reach under the intake manifold to find them. 2 out of 2 of these I haveworked on with a similar problem have had that issue. Likely much the same setup on the 1.8.

I have seen others replace MAF sensors thinking that was the issue only to find the same thing.
thejazzpianoma, Jul 31, 6:54pm
SNAP!

BTW, sometimes you have to open the vacuum hoses out and look really carefully to see the problem.
franc123, Jul 31, 7:03pm
Have eliminated any external leaks, no signs of a head gasket issue, both the ETB and MAF sensors have been swapped out with known good ones. Doesn't have an EGR valve. The manifold vacuum is very low however which made me think that the seals might have gone. Other than that I'm thinking that the cam timing might have gone out somehow!
wimwom, Jul 31, 7:03pm
The hose i refer to is about a inch to inch and a half in diameter, it links manifold to throttle body if my memory serves me well.Has a annoyingly placed spring clip on one end!
wimwom, Jul 31, 7:05pm
Why no egr!Those motors will not run properly without one or with it blocked off as suggested on many websites.The egr requires it as part of its function. I have no knowledge of the 1800 motor, just the 1600 but feel it will be the same! There might be your problem!
wimwom, Jul 31, 7:06pm
sorry, that should read the ecu requires it.
unbeatabull, Jul 31, 7:08pm
If you have any air leaks, get a can of some decent brakecleen or flammable product and spray it around all the manifold joins, hoses etc, engine will miss/die when ya find it! I've found Wynns Brakecleaner the best for this.
franc123, Jul 31, 7:12pm
x1
The head has provision for an EGR valve which sits in a passage between No4 intake and exhaust ports, the passage is blocked with a factory plate and gasket, it hasn't been removed deliberately. The external hoses have all been checked and are OK, there are none underneath except for the supply line for the servo and solenoid that operates the intake flaps.
franc123, Jul 31, 7:15pm
Done that already, didn't prove a damn thing! Its hard to get to the manifold joint because it fits very closely with the head, ie there isn't the usual gap were a gasket would fit.
wimwom, Jul 31, 7:16pm
Ok, sorry lost to help.Had those problems with mine.I went on line and found many threads stating fault would be EGR, cost of replacement was expensive. I built a gasket without the holes and blocked it, caused no end of grief and showed up on scan tool. Guy doing scan explained that the GM ecu had to have egr!
That hose had the hole in such a place that spraying liquid at it never showed the problem up. I was damned pleased to be shot of my astra!
mugenb20b, Jul 31, 7:23pm
Maybe I'm on the wrong track, but have you checked the brake booster hose / pipe!
franc123, Jul 31, 7:29pm
Yeah sure have, the port is where the vacuum gauge is attached to at present.
donz01, Jul 31, 7:42pm
When you say rough idle, do you mean its revs are fluctuating up and down or is it running rather rough with a miss while it idles. Our one used to rev up and down with out missing from 700rpm to 1200 rpm. I removed the throttle body and gave it a good clean. there was a very small vacum port (2mm drill bit just fits) that was gummed up. Once cleaned the car would idle normally.
doctor_evil99, Jul 31, 7:48pm
Test the coil pack - mine ran rough for a while. They thought it was the ERG valve.Turned out to be nacked coil pack.
treachug, Jul 31, 7:50pm
I'd be looking at ECU. Had similar on a '98 X18XE1. Ran rough, often stopped & wouldnt start or hard to start, once started often went ok then off song again. Did all tests, changed lots.I have the OP-com tool & it kept telling throttle body fault - changed that no difference.
One of the factory fixes on X18XE1's was to remove EGR & fit factory blank off plate. Did so on this 1.8, no difference. Purchased new ECU from UK car ran best it ever has. Could try reflashing ECU with latest software but may not be enough.
franc123, Jul 31, 7:53pm
Running rough and missing, rpm stays roughly (!) where it should be. Will check the vacuum port. Oh it only brings up a fault code for lean exhaust, something I already know from watching the 02 sensor outputs.