Where does this vacuum line go?

[DamoMonster]

Hey there,

Fixing up my new to me 1988 L200 with a 4G63 SOHC and I have this random vacuum line hanging off the air intake - anyone know where it was meant to go? I can’t upload a picture for some reason, but there’s a round disk looking object on the metal snorkel end of the air intake, it has a vacuum line that comes off it and it looks to be mounting hooks for it leading around to the side of the carburettor maybe?

Cheers

[DamoMonster]

[FMS88]

That sounds like the vacuum line to the thermo sensor in the air cleaner. The free end should connect to the brass multi-port vacuum tree that's screwed into the intake manifold below the carburetor. The disk shaped object on the snorkel, the thermo sensor and vac lines are all part of the intake air temperature control system that's engaged during engine warm up.

[xboxrox]

Yep as FMS says ~ I disconnected mine & capped the vacuum source nipple because no really cold weather here in Hawaii PLUS if the temperature sensor inside the air intake malfunctions (mine did) the default snorkle air valve opens causing the engine to inhale hot exhaust air continuosly...

[SubGothius]

Just approved a post with photo from OP that got auto-modded for some reason.

Now that we can see the hose you mean, a correction to FMS88's reply: that hose should plug into the air temp sensor on the bottom of your air cleaner. Then the other hose barb on that sensor connects a hose to the vac tree on the manifold.

BTW, pretty sure the intake snorkel has the hot-air flap closed by default, only pulled open by vacuum when the air-temp sensor in the cleaner housing allows vacuum to pass. At least, that's how the snorkel works for my 2.6L and other carb'd vehicles I've owned. Which makes sense, as default modes are typically for "normal running" conditions, with the deviation from default being for special-case scenarios (frigid-temp warmups in this case).

[DamoMonster]

Just approved a post with photo from OP that got auto-modded for some reason.

Now that we can see the hose you mean, a correction to FMS88's reply: that hose should plug into the air temp sensor on the bottom of your air cleaner. Then the other hose barb on that sensor connects a hose to the vac tree on the manifold.

BTW, pretty sure the intake snorkel has the hot-air flap closed by default, only pulled open by vacuum when the air-temp sensor in the cleaner housing allows vacuum to pass. At least, that's how the snorkel works for my 2.6L and other carb'd vehicles I've owned. Which makes sense, as default modes are typically for "normal running" conditions, with the deviation from default being for special-case scenarios (frigid-temp warmups in this case).

Thanks so much for the replies - I lifted the Air Cleaner off and have now got more mysteries...



I can see the two points you've mentioned on the bottom of the Air Cleaner, but I've now found another hose disconnected and an empty barb - any idea what goes where?



Really appreciate the help so far!! Cheers

[FMS88]

Yes, pictures definitely help! Not sure about the latest hose. Does the other end attach to the carburetor or manifold? If the manifold, it could go to the air cleaner thermo-switch. As to the open port, is there vacuum hose routing diagram applied to the under side of the hood? If not, is there an identifying number on the carb top, or one on the tag next to the left of the accelerator pump and above your hand seen in Carb.jpg? Identifying the carb could help us find info about its vacuum lines and ports.

Is there a vacuum line from the distributor advance to the carburetor? If not, the open port you're pointing to may be for the distributor advance.

Lastly, in the Vacuum.jpg picture in Post #2, it looks like the shroud over the exhaust manifold is missing. Without it and the flexible hose/duct from the shroud to the air cleaner snorkel, less warm air will be directed to the carburetor during warm up.

[SubGothius]

Is there a vacuum line from the distributor advance to the carburetor? If not, the open port you're pointing to may be for the distributor advance.

Yeh, that position on the carb does look like about the right spot for "ported" vacuum that would operate the distributor vac advance off-idle.

[xboxrox]

I do stand corrected..! BUT, that thermo vacuum valve in the air cleaner on my truck did/does malfunction... I discovered the snorkel flapper valve open continuously by chance when once having the engine running with the air intake hose off the air cleaner casing... I tried adjusting the bi-metallic contacts to no avail as that valve just kept letting vacuum pass through even with the engine warm & hot... It's worth checking it's proper operation after you get all the vacuum hoses sorted and connected...

Default is no vacuum it stays shut to draw in cold outside air