Vacuum leak?

This area is for posting questions/information concerning 1964-66 year Thunderbirds NO FOR SALE POSTINGS

Moderator: redstangbob

Nirich
Posts: 36
Joined: Sun Sep 02, 2018 5:04 pm

Vacuum leak?

Post by Nirich »

My '66 HT (ex California car) idles a little fast and when listening to the exhaust it 'fluffs' (highly technical description.....). Someone suggested that it was running a little lean due to a vacuum leak. The colour of the exhaust pipe is a dark brown not light as i would expect if it was running lean.
Any suggestions on where or what to look for?
Attachments
TBird2.jpg
1966 HT, Q code, A/C, Silver Rose in colour, red interior and lives in Auckland, New Zealand.
VTCI ID# 12903
User avatar
RedBird64
Posts: 2234
Joined: Wed Oct 31, 2012 11:42 pm
Location: Bothell Wa.

Re: Vacuum leak?

Post by RedBird64 »

You can pinch off any vacuum lines coming off the manifold and see if the idle changes. I would connect a guage and monitor vacuum while you do that. Any change will direct you towards the offender.
If you really want to make sure, get it hooked up to an exhaust analyzer. If it is lean, it can be anything from a carb adjustment to leaking gaskets or internal issues.
You do not want to let these engines run lean for very long. You'll end up with a burnt valve.

BTW, brown inside ex pipe is fine.

Good luck,
Scott
1964 Coupe Wimbledon white/Rangoon Red w/black int. Owned for 42 years. It was my folks car before that (second owners). VTCI # 12013.
User avatar
paulr
Posts: 1800
Joined: Mon Nov 05, 2012 12:03 pm
Location: Seattle

Re: Vacuum leak?

Post by paulr »

Nothing to add--Scott's diagnosis outline is complete.
However, nice car! That 1966 Silver Rose (Code O) is never seen. I've seen it on Lincolns the same model year but not Tbirds. There can't be more than a handful of cars still rolling out there with this color. I believe it was one year only color. (correct me please if I'm wrong.) It looks amazing!
Paul
VTCI 12014
Registry 45122
'64 Landau HT
"Beer, now there's a temporary solution!" ~Homer Simpson
jtschug
Posts: 1472
Joined: Fri Sep 11, 2015 1:33 pm

Re: Vacuum leak?

Post by jtschug »

Here is a trick to use with caution. Do it in a well-ventilated area with a fire extinguisher handy.

I use starting fluid to find vacuum leaks under the hood. Spray a small amount on fittings, hoses, joints, gaskets where you think there is a vacuum leak. If the idle speed changes when you spray the fluid on, then you know there is a leak.
1966 Thunderbird Convertible (Emberglo / White-Emberglo)
Modified 428 - stroked, rollercam, aluminum top end, headers
Livermore, CA
Nirich
Posts: 36
Joined: Sun Sep 02, 2018 5:04 pm

Re: Vacuum leak?

Post by Nirich »

Thanks Scott. I squeezed a few hoses today with the car running.......no change in idle. However i did discover the carb leaking petrol slightly which makes me think that the whole carb is pretty tired (possible air leak via butterfly shafts?), one choke tube missing and the other hanging loose over the manifold. I will get those sorted first and then see if i still have a leak somewhere. Are the choke tubes the same as the ones for '63/'64 cars?

Silver Rose is a one year colour (part the reason i bought it), the bonus is the Q code motor.
1966 HT, Q code, A/C, Silver Rose in colour, red interior and lives in Auckland, New Zealand.
VTCI ID# 12903
User avatar
sseebart
Posts: 1686
Joined: Sun Jan 22, 2012 1:45 am
Location: Northern California
Contact:

Re: Vacuum leak?

Post by sseebart »

Nirich wrote: Thu Nov 29, 2018 9:45 pm (possible air leak via butterfly shafts?),
This is a pretty common point of failure for the Autolite carbs. Typical rebuild kits don't address it--please let us know if it is indeed out of spec and how you are about to sort it out.

~Steve
bbogue
Posts: 850
Joined: Wed May 01, 2013 3:04 am

Re: Vacuum leak?

Post by bbogue »

The flat plates that seal the carb are often warped due to repeated repairs and over tightening. Accelerator pump cover, power valve cover, secondary diaphragm cover and carb base where it meets the spacer can all be warped. Rubbing the parts on sandpaper atop a flat surface works wonders.
Additionally, the vacuum advance diaphragm can leak. Disconnect the line to the VA can and try to pull a vacuum on the can. If it won’t hold vacuum the diaphragm is shot.

Bill
Past owner 1961 Thunderbird - Heritage Burgundy Metallic

If there are no dogs in heaven, send me where they went. - Will Rogers
Nirich
Posts: 36
Joined: Sun Sep 02, 2018 5:04 pm

Re: Vacuum leak?

Post by Nirich »

Update............long time coming.

I had the leaky carby rebuilt, new intake manifold spacer and gaskets, new distributor vacuum, new set of spark plugs and the car runs a LOT better. Much more responsive and hauls a$$. BUT I still have a vacuum leak.

Over the last couple of months I have tried pinching various vacuum hoses and sprayed starting fluid around without any success. So I started replacing vacuum hoses all through the engine bay from the manifold back to the big vacuum can on the bulkhead and the hose that went to the A/C can hidden under the right front fender. Even replaced the PCV valve. Obviously the few hoses that went in behind the dash I haven't done. Still have a 'fluffing' exhaust.

I have checked and replaced the vacuum hoses at the rear vents . The door lock switch works, the rear vents work and the windows go up and down, the a/c and fan works but the emergency brake release doesn't when I shift the car into drive or reverse (manual release works fine).

Do I have an issue with the EB vacuum diaphragm or the neutral safety switch or am I doomed to remove the dash?

Am losing the will to live..............
1966 HT, Q code, A/C, Silver Rose in colour, red interior and lives in Auckland, New Zealand.
VTCI ID# 12903
User avatar
sseebart
Posts: 1686
Joined: Sun Jan 22, 2012 1:45 am
Location: Northern California
Contact:

Re: Vacuum leak?

Post by sseebart »

Nirich wrote: Fri Feb 01, 2019 8:19 pm Do I have an issue with the EB vacuum diaphragm or the neutral safety switch or am I doomed to remove the dash?

Am losing the will to live..............
Thanks for sending along an update--future owners will thank you as well.

I looked through this thread, but didn't see if your car has A/C or not. If so, there are lots of vacuum lines behind the dash. If not, well . . . there are still plenty back there to cause trouble.

The good news is that while pulling the dash is a big job, it's not terribly difficult to do. Paul is in the habit of pulling the dash at least once a year, at this point, just for fun I think. I have a pictorial guide here: http://thunderbird.seebart.org/photo-jo ... rd-removal. And, of course, everyone here is ready to help.

Keep us posted!

~Steve
Nirich
Posts: 36
Joined: Sun Sep 02, 2018 5:04 pm

Re: Vacuum leak?

Post by Nirich »

Soooooo...........how long will it take Paul to get to New Zealand?
My dash awaits.......... :smile:
1966 HT, Q code, A/C, Silver Rose in colour, red interior and lives in Auckland, New Zealand.
VTCI ID# 12903
User avatar
paulr
Posts: 1800
Joined: Mon Nov 05, 2012 12:03 pm
Location: Seattle

Re: Vacuum leak?

Post by paulr »

sseebart wrote: Fri Feb 01, 2019 9:37 pm [there are lots of vacuum lines behind the dash. If not, well . . . there are still plenty back there to cause trouble.

The good news is that while pulling the dash is a big job, it's not terribly difficult to do. Paul is in the habit of pulling the dash at least once a year, at this point, just for fun I think.
~Steve
Hardy har har--only every other year, Steve. Not my fault I keep finding better dashboards in the rafters.

So, there's a spitting chance that an otherwise well cared for vehicle has A/C lines integral to the dash plenum that are original and therefore pretty dehydrated after 53 years. Resin dries, they stiffen up and lose grip on their ports. Since the HVAC on an A/C car includes around 30 ports and connectors that you can't see, it's good odds problems exist therein. It doesn't do any good to replace the one or two that you can reach by hand underneath, if 20 others you can't reach still leak.

If you haven't done much searching yet, here's a start. Discussions with info on how many dash lines exist, locations, sizes, routing, etc. This is just a sample; there are many threads to look for. I also included the most correct vacuum map I've ever found, though your '66 manual has separate vacuum maps for most systems. Remember, any individual line can have one or more connectors, many of which could be leaky. Dash removal could be good 2-3 week winter project (coming up in a few months, right?), and the vacuum lines are cheap. You get a chance to test all the vac motors for r&r, clean and polish out the plenum airways, even repad the blend doors with new neoprene. All easy and cheap. Anyway, it would remove all doubt. Best of luck.
http://www.vintagethunderbirdclub.net/p ... 543367c2fa
http://www.vintagethunderbirdclub.net/p ... 543367c2fa
https://www.parts123.com/birdnest/pdf/V ... agrams.pdf

By the way, my door locks all worked, even though the original hoses were leaky as heck. After replacing with tight new connections, they worked with way better snap and now hold vacuum for about 5 minutes after the car turns off. Something else under the dash.

Man, I LOVE the color of that car, it's my new favorite. Can't ya just see Sammy Davis, Jr. in that?
Paul
VTCI 12014
Registry 45122
'64 Landau HT
"Beer, now there's a temporary solution!" ~Homer Simpson
David Langhorne
Posts: 735
Joined: Sat Dec 17, 2011 6:40 am
Location: England

Re: Vacuum leak?

Post by David Langhorne »

I'm not sure what sound you are getting but it sounds a bit vague. Maybe you could put it on youtube? Are you sure it's not coming from the exhaust manifold? You could test the exhaust gas with a cheap Gunson analyser. I have one which I use to set up the LPG mixture on my car.
Here is a link to one on ebay in UK similar to mine.

https://www.ebay.co.uk/itm/Gunsons-Gast ... :rk:1:pf:0
Dave Langhorne 65SL
UK
Nirich
Posts: 36
Joined: Sun Sep 02, 2018 5:04 pm

Re: Vacuum leak?

Post by Nirich »

Thanks for the response Paul!
Actually, all i saw was.......blah blah blah blah..........you're going to spend 2-3 weeks in NZ and you love the colour..........................
Oh, and some links to pretty pictures.
1966 HT, Q code, A/C, Silver Rose in colour, red interior and lives in Auckland, New Zealand.
VTCI ID# 12903
Nirich
Posts: 36
Joined: Sun Sep 02, 2018 5:04 pm

Re: Vacuum leak?

Post by Nirich »

David Langhorne wrote: Sat Feb 02, 2019 4:46 am I'm not sure what sound you are getting but it sounds a bit vague. Maybe you could put it on youtube? Are you sure it's not coming from the exhaust manifold? You could test the exhaust gas with a cheap Gunson analyser. I have one which I use to set up the LPG mixture on my car.
Here is a link to one on ebay in UK similar to mine.

https://www.ebay.co.uk/itm/Gunsons-Gast ... :rk:1:pf:0
The 'fluffing' description came from an old school mechanic who said it was a sign of a lean running engine. He is supposed to be retired (he is nearly 70) but still works at the same establishment he started 35 years ago and recently handed over to his son. He particularly likes my car as he, back when he was a young apprentice, drove and worked on a '66 TBird that was imported 50 years ago by the car sales business he worked at. Rare to see an American car here back then as the vast majority were English imports.

The running lean was confirmed when I changed the spark plugs, they were a very light gray. The exhaust doesn't have a leak and one manifold was warped when it arrived in NZ, which was skimmed flat and re-attached. To import a vehicle to NZ it goes through a process called 'Compliance' before being able to be registered for the road. Compliance is TOUGH. Any body or chassis rust is a fail. Any older vehicle with drum brakes is automatically a fail until the brake pads and slave cylinders are replaced. A leaky radiator is a fail. An unsecured battery is a fail. Then we get to the ball joints..........

Anyway, an exhaust testing unit is not a bad idea and might help keeping things tuned.

Cheers,
Nick
1966 HT, Q code, A/C, Silver Rose in colour, red interior and lives in Auckland, New Zealand.
VTCI ID# 12903
jtschug
Posts: 1472
Joined: Fri Sep 11, 2015 1:33 pm

Re: Vacuum leak?

Post by jtschug »

You don’t have to pull the dash for the brake release or the neutral switch, but for A/C vacuum lines you will. I replaced all mine with silicone while I had the dash out. They will now outlive me. If you do it, you may want to freshen up the vacuum motors as well
1966 Thunderbird Convertible (Emberglo / White-Emberglo)
Modified 428 - stroked, rollercam, aluminum top end, headers
Livermore, CA
Post Reply