Manifold vacuum leaks

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Manifold vacuum leaks

Postby Chas54 » Tue 02.08.2022, 16:07

Got the car out yesterday , it last ran 3 days ago perfectly well , and it was running rough again.

Checked with elanscan and the vacuum was poor at about 0.65 bar. I last did an elanscan run on the 8th July and the vacuum was around 0.35bar, this was because i was due for an MOT.

I could only think i must have a vacuum leak somewhere so after a check round and not finding anything i looked on line for info about smoke generators to fill the manifold and plenum etc .

I found some simple instructions from an American on you tube about how to make you own generator from a jam jar , some tubing, a soldering iron and some baby oil.

Its a simple matter of drilling 3 holes in the jam jar lid. One for the air inlet ( i used my compressor) , one for the soldering iron and one for the smoke outlet hose.. I put some baby oil on a scrap piece of paper towel , switched on the soldering iron and watched as it produced smoke .

I disconnected the MAP sensor point and put my smoke machine outlet tubing onto it , applied some very low pressure air to the jar and filled the whole system with smoke.

I had the big air inlet hose off the throttle body so i noticed pretty well straight away that there was a small amount of smoke passing the throttle butterfly . I think the only trace of smoke i should find there is what is passing through the IAC port.
Anyway i will have to inspect the throttle seating but have to wait for a gasket as i know they generally come off in pieces . In the short term i wiped the assembly out with thinners and exercised the mechanism fully, The smoking was reduced so i reassembled and its now running perfectly well again.

The main point of this post is to draw attention to the simple method of producing a manifold leak detection smoker.
Chas54
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Re: Manifold vacuum leaks

Postby Tuga2112 » Tue 02.08.2022, 16:18

Ive seen those smokers on youtube before. never made one. mostly because my soldering iron is needed for... soldering electronic components.
its good to know that the principle works.

have you got any pictures of your contraption for illustration purposes ?
1991 elan se
1991 elan se project
91 MR2 Turbo (import) project
94 Celica GT4 (Import)
94 4Runner
98 Celica SR

too many projects. not enough sunny days :(
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Re: Manifold vacuum leaks

Postby Chas54 » Tue 02.08.2022, 19:54

smoko .png


I had actually put the bits of pipe away , but i only used the clear reinforced petrol pipe type hoses.

The hole each side of the soldering iron for a short piece of tube to blow air in, the other i had about 2metres of the same tubing pushed on to the MAP sensor point on the RHS of plenum. That enbled me to leave the contraption on the bench.

I was surprised how convincing the test was. I pulled off a couple of the longer vacuum lines and they had smoke at a reasonable rate escaping. I took the oil cap off the cam cover and smoke issued from there as well.

I think my jar is pictured above.
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Chas54
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Posts: 156
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