Manifold preheat tubes

Hi there. I discovers my manifold pre heat tubes (i think thats what they are) have holes at the bends just after they rise up from the bottom tin. Are replacements available for these or is there a durable repair I can do?

Thanks in advance!

That's where they usually go.
Depends how bad the holes are, I've patched one of mine before but if it's bad enough it's better off in the long run to just replace the manifold.

chillihilli wrote:Hi there. I discovers my manifold pre heat tubes (i think thats what they are) have holes at the bends just after they rise up from the bottom tin. Are replacements available for these or is there a durable repair I can do?

Thanks in advance!

I replaced Mine later last year with a good used one from Stokers Siding VW Parts..

I had My original repaired a couple of times but once they start to rust its hard to stop them...

Good used ones are still available [single port] and new dual port manifolds can be bought,,


cheers

LEE

PS: Can't remember whether You have single or dual port engine...

Thanks Lee. I am dual port. CVD have them for $130 posted. Have. Y o had any experience adding in the vac port for the autostick?

Mine are caked over and blocked.
I know they add heat to the fuel mixture to improve combustion and stop icing but I dont seem to suffer and have assumed that they were more eurocentric in their necessity? ( or for people that live in Scone LEE)
What are the symptoms I would suffer if they were a problem?
Mitchell

Much smoother when it works
I have been told they are required on ALL weather conrditions - more so in colder.

Have a look in the mornings and see if you have condensation after a couple of minutes.
You may be surprised

waltermitty wrote:Mine are caked over and blocked.
I know they add heat to the fuel mixture to improve combustion and stop icing but I dont seem to suffer and have assumed that they were more eurocentric in their necessity? ( or for people that live in Scone LEE)
What are the symptoms I would suffer if they were a problem?
Mitchell

Mitch,

I get away with none here in PMQ but that said I would rather have working heat risers. Without them, in winter especially, you need to spend a lot of time warming up, otherwise you get symptoms similar to not enough or no choke eg. stalling conveniently when you've just jumped into a gap in the traffic from an intersection. Other symptoms include flat spot (semi stall) or if the inlet manifold really ices up the engine can just "die" on you and take a lot of effort to get started again.

Regards,

Matt.

chillihilli wrote:Thanks Lee. I am dual port. CVD have them for $130 posted. Have. Y o had any experience adding in the vac port for the autostick?

Yes
I just drilled the hole where I wanted the piece of pipe welded in and My Son did the job...

just about 75mm of 12mm or 1/2 inch of thin steel pipe

I did want it angled upwards like the original but My Son welded it in straight...

anyway works great... no problems..

cheers

LEE

PS: You could cut the original pipe off and have it welded to the new manifold.. Lee

Chilli,
I've got a spare that has had the tubes gone through
(I'll make sure) and is for an A-S (or Type 2). I'll do a little welding/grinding as one of the bolt holes is a teensy ordinary.

PM if you want to buy...don't expect a blistering response though..



Regards
Ctefeh

ctefeh wrote:Chilli,
I've got a spare that has had the tubes gone through
(I'll make sure) and is for an A-S (or Type 2). I'll do a little welding/grinding as one of the bolt holes is a teensy ordinary.

PM if you want to buy...don't expect a blistering response though.

Regards
Ctefeh

Thanks for the offer Ctefeh. I got out an old handbrake cable and stuck it in a drill and gave them a good reaming. There was a lot of crap came out, but I don't think they are blocked (are they supposed to blow throw from one side to the other?).

I found some Pirtek muffler/exhaust repair tape which is self-amalgamating with heat. I'll try that first with hose clamp on it and see how it goes.

@ Waltermitty and Matt - I could run them with the hole - I don't think it was that much of a detriment as the carb would have still been getting some warmth. BUT I am trying to remove any potential source of poor performance as am planning to put it in to service as a city commuter.

And thanks Lee - your pics tell a thousand words as always. In the interests of quality work if I go the new manifold route I would take it to someone who knows how to weld.

Cheers Pete.

Hi
I didn't know mine was rusted out.. it was just the black exhaust marks on the yellow plate behind the alternator that I saw...
Yes
the hot air is supposed to flow from one side to another...
different mufflers etc do it different sides..

after repairing your preheat tubes I suggest pouring some oil in there to stop any further rust for a while...

cheers

Lee

68AutoBug wrote:the hot air is supposed from one side to another...
different mufflers etc do it different sides..

cheers

Lee

That's really interesting Lee as I could not pass a hand brake cable from one side to the other. Nor did air blow through when I shoved my compressor blower in there. I will patch it and see if it blows out again. It may be my next project - replace the manifold and clean the carb.

waltermitty wrote:Mine are caked over and blocked.
I know they add heat to the fuel mixture to improve combustion and stop icing but I dont seem to suffer and have assumed that they were more eurocentric in their necessity? ( or for people that live in Scone LEE)
What are the symptoms I would suffer if they were a problem?
Mitchell

Mine r too... I think thats why my engine misses and splutters half the time in the first 5-10 minutes. I thought it had to be something to do with the dual throat webber...with the climate down here in Melbs it is a problem😠

Hi Pete

My Son has a welding ticket which comes in handy...

I found no problems when the heater pipe had broken thru..
maybe just leaking a bit.. well, I don't suppose much exhaust goes thru when its clogged up..

but when it clogged going to Sydney , and the temperature dropped down to 2-3 degrees... My engine revs slowly declined then stopped..
when i saw the ice on the inlet manifold...
I taped up My vents in the engine lid plus those below the rear window... so all air was coming from the hot air box under the engine... in thru the yellow colored hose..
[in photo]

so, they are needed in Scone... lol

cheers

LEE