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| Persistent vacuum leak http://auszookers.com/forum/viewtopic.php?f=5&t=40903 |
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| Author: | Benchai [ Wed May 15, 2013 8:17 am ] |
| Post subject: | Persistent vacuum leak |
Jake's WT(88 G13A) has been having an ongoing issue with what we believe is a substantial vacuum leak. When we got it on the road it ran sweet, then out of the blue it wouldn't idle below 2000rpm and rough as guts. Did the check around for leaks etc, and bit the bullet and put a kit through the carby. Ran sweet again, after a couple of days same problem, though not quite as bad. Pulled carby off, check it was put back together ok, and tried some gasket goo on the base plate gaskets in case of distortion or something bizarre. Same deal, ran sweet then the text comes - it's gone to shit again. This time we swapped carby with my parts car, same all over, though it lasted a couple of weeks this time. Got Jake to make a new pair of base plate gaskets because the goo had damaged them when we changed carby. This time started and ran fine but was playing up again before he left the carpark. So, my next step is to change inlet manifolds. Am I on the right track, any other suggestions? |
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| Author: | Zook101 [ Wed May 15, 2013 8:21 am ] |
| Post subject: | Re: Persistent vacuum leak |
Hey mate, Does the Idle go up and down a lot ?? |
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| Author: | Benchai [ Wed May 15, 2013 8:32 am ] |
| Post subject: | Re: Persistent vacuum leak |
Yeah, it probably does when it's in a play up cycle. It runs perfectly after we bolt carb back on, then spontaneously plays up until we deal with it. |
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| Author: | droverdave [ Wed May 15, 2013 8:34 am ] |
| Post subject: | Re: Persistent vacuum leak |
Get the thing running and spray some sort of aerosol where you suspect the leak is, you will hear the engine react if you found the leak. |
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| Author: | stockman [ Wed May 15, 2013 8:36 am ] |
| Post subject: | Re: Persistent vacuum leak |
When you did the carby did you replace the fuel filter? It could still be carby related and could be something as simple as the fuel pump diaphragm is breaking down and ending up in the carby. Servicing a carby is a great excuse to fit a 2nd filter between the pump and the carby. |
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| Author: | Benchai [ Wed May 15, 2013 9:04 am ] |
| Post subject: | Re: Persistent vacuum leak |
Fuel filter is new from the build up, and there was no sign of foreign bodies in carb when we had apart those couple of times. Have tried the aerosol, almost wondering if manifold is cracked where carb bolts through or where we can't get the spray to |
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| Author: | Zook_Fan [ Wed May 15, 2013 9:05 am ] |
| Post subject: | Re: Persistent vacuum leak |
Go and buy a metre or so of vacuum hose and replace all of the hoses on the carby and inlet manifold. Check that every hole in the manifold has a hose on it going to somewhere. Mine use to do this and it was one of the hoses from the manifold to the air cleaner box use to slip off. Fixed that by trimming it shorter so a 'new' end piece of the pipe butted up to the manifold making a tighter fit. My 1.6 ran as you describe. Would be fine for a while then all sorts of issues. After replacing all the hosing around the carby and pushing air through the old ones with the compressor I found heaps of little cracks that would open up depending on how the hose was ran. My theory was when it was put on to start with they were all either old and about to crack or had cracked but the way the loops were it held the cracks shut. |
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| Author: | tanshi [ Wed May 15, 2013 9:09 am ] |
| Post subject: | Re: Persistent vacuum leak |
ive also found it can be caused by junk in the water hoses under the carby. pull each one off in turn and clean it out. make sure they go back on in the right places |
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| Author: | Benchai [ Wed May 15, 2013 9:33 am ] |
| Post subject: | Re: Persistent vacuum leak |
I was thinking of plugging all the small lines except for the vacuum advance and charcoal cannister. Is this going to cause more problems than it solved? We have ascertained that all automatic choke functions do not function Tanshi, what do these water hoses service? |
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| Author: | Zook_Fan [ Wed May 15, 2013 10:13 am ] |
| Post subject: | Re: Persistent vacuum leak |
I'd say it will cause more problems but don't know for sure. On a car that I purchased all of the hoses were doubled back onto them selves and it ran terribly. After switching them back to how they were suppose to be it ran much better. The water hoses are part of the automatic choke system. |
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| Author: | tanshi [ Wed May 15, 2013 10:25 am ] |
| Post subject: | Re: Persistent vacuum leak |
yep they work the auto choke. the blockages can open and close the choke without warning on need. are you sure the auto choke doesnt work at all? |
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| Author: | want33s [ Wed May 15, 2013 1:29 pm ] |
| Post subject: | Re: Persistent vacuum leak |
Could also be a brake booster problem, easy enough to check. |
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| Author: | stewy91 [ Wed May 15, 2013 4:56 pm ] |
| Post subject: | Re: Persistent vacuum leak |
ive got a spare manifold if that's what it comes down to |
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| Author: | SierraFreek [ Wed May 15, 2013 5:32 pm ] |
| Post subject: | Re: Persistent vacuum leak |
Hey Guys, just an update on the issues with my car Today, I spent the afternoon replacing the inlet manifold gasket and as many of the vacuum hoses as I could with the metre of hose that we bought. All was sweet, started, idled, but only in neutral. The second I put it in reverse to drive it out of the shed, she died. I thought this was very odd, so i put it back in neutral, started her up again, no issues, idles at around 850-950, then I put it into first gear (clutch in, obviously) and dead. Second, dead. Third, dead. As soon as it goes into any gear, it basically cuts the ignition off, and the engine just stops. Revved the engine up to 1500rpm, same issue, just dies, didnt try going any higher, but I'm inclined to think that the issue would still be present. If someone knows whats happening here, the help would be greatly appreciated. Thanks in advance |
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| Author: | Benchai [ Wed May 15, 2013 8:13 pm ] |
| Post subject: | Re: Persistent vacuum leak |
Had a look at it tonight and it's the fuel cut off solenoid in the carby, which for some reason after changing the manifold is cutting off when in gear. I'm thinking we'll have to trace through where the earth line is open when in gear and bypass it. |
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| Author: | royce [ Wed May 15, 2013 8:51 pm ] |
| Post subject: | Re: Persistent vacuum leak |
unplug the vacuum solenoid for the EGR (diaphragm actuator on manifold under the carby) there might be something iffy in its control box, that about the only electrical link with the gearbox |
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| Author: | Benchai [ Thu May 16, 2013 8:50 am ] |
| Post subject: | Re: Persistent vacuum leak |
Checked the earth line from the fuel solenoid, and it's open when in gear and closes in neutral. Dodgy bros fix ; cut earth and attatch direct thereby bypassing whatever is opening and closing this circuit. Ignition on, solenoid on. Not sure if there is a difference between 88 and 89 in terms of pollution and wiring, but we're marrying an 89 carb to an 88 everything else. That fixes the electrical issue, hopefully the manifold swap will remedy the other. Thanks for all your help guys |
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| Author: | royce [ Thu May 16, 2013 10:13 am ] |
| Post subject: | Re: Persistent vacuum leak |
I would stick another earth lead from engine to body just to be sure other funny business isnt going on |
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| Author: | Benchai [ Thu May 16, 2013 11:18 am ] |
| Post subject: | Re: Persistent vacuum leak |
OK, will do |
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