740 Throttle body

  • Thread starter Thread starter Bill
  • Start date Start date
From a point at sea, to the circles of your mind, this is Bill:

Can anyone point me in the right direction.
Click to expand...

It's under the inlet manifold - that big aluminium thing with legs on
top of the engine. There's a black rubber boot that connects the air
flow meter to the throttle body. If you operate the accellerator cam
(the accellerator cable attaches to it) you will see a linkage moving
- follow this linkage to the throttle body.


--

Stewart Hargrave

A lot faster than public transport


For email, replace 'SpamOnlyToHere' with my name
 
Stewart Hargrave said:
From a point at sea, to the circles of your mind, this is Bill:



It's under the inlet manifold - that big aluminium thing with legs on
top of the engine. There's a black rubber boot that connects the air
flow meter to the throttle body. If you operate the accellerator cam
(the accellerator cable attaches to it) you will see a linkage moving
- follow this linkage to the throttle body.
Click to expand...

Thanks Stewart, I will have another look later. I got the Haynes manual you
recommended (the black covered one). I see why it is preferred over the new
one, certainly more comprehensive, except for the throttle body!

Bill
 
Stewart Hargrave said:
From a point at sea, to the circles of your mind, this is Bill:



It's under the inlet manifold - that big aluminium thing with legs on
top of the engine. There's a black rubber boot that connects the air
flow meter to the throttle body. If you operate the accellerator cam
(the accellerator cable attaches to it) you will see a linkage moving
- follow this linkage to the throttle body.
Click to expand...

I have just been out and had another look. As you say there is the rubber
boot. The throttle body is the bit between the boot and the inlet manifold,
correct? To remove it is it just a simple operation of undoing the worm
drive clip that holds the boot to the TB, removing everything connected to
it, then undoing the nuts. There is a microswitch attached which is
operated by the linkage, but looking at my picture again I don't think it is
attached to the TB, just blocks easy access to the nut. Is the throttle
position switch inside the TB, or does it remain in the inlet tract when the
TB is removed.

Apologies for so many questions, but I would rather ask before I start than
get stuck halfway through the job!

Thanks again

Bill
 
From a point at sea, to the circles of your mind, this is Bill:
The throttle body is the bit between the boot and the inlet manifold,
correct?
Yep.

To remove it is it just a simple operation of undoing the worm
drive clip that holds the boot to the TB, removing everything connected to
it, then undoing the nuts.
Click to expand...

Never needed to get that far myself, but it sounds about right. I
would anticipate that there would be a gasket or O-ring between it and
the manifold.
There is a microswitch attached which is
operated by the linkage, but looking at my picture again I don't think it is
attached to the TB, just blocks easy access to the nut. Is the throttle
position switch inside the TB, or does it remain in the inlet tract when the
TB is removed.
Click to expand...

My car is a bit earlier than yours ('87) and doesn't have a TPS, so I
don't know the answer to that. AIUI, unless you have a catalyst, K-Jet
doesn't need one. Thinking about it, mine too has a microswitch that
I've puzzled over. It's not connected to anything, so my guess is that
it is there for models that have some sort of constant idle control -
it seems it would only sense when the throttle is fully closed - and
is redundent on mine.

TBH, unless you have a problem specifically related to the throttle
valve I wouldn't be going to the trouble of removing it. Clean and
lubricate the outside linkage mechanism, make sure this is working
smoothly, and opening and closing properly. There is much less inside
the TB than outside it (only the butterfly valve of the throttle).
It's not nearly as complicated as a carburetter.


--

Stewart Hargrave

A lot faster than public transport


For email, replace 'SpamOnlyToHere' with my name
 
Weird, that's the first time I've seen that setup, looks almost like an '81
or earlier 240 except for the distributor on the back of the head. Was KJet
cheaper than LH Jet or something?
 
I have just been out and had another look. As you say there is the rubber
boot. The throttle body is the bit between the boot and the inlet manifold,
correct? To remove it is it just a simple operation of undoing the worm
drive clip that holds the boot to the TB, removing everything connected to
it, then undoing the nuts. There is a microswitch attached which is
operated by the linkage, but looking at my picture again I don't think it is
attached to the TB, just blocks easy access to the nut. Is the throttle
position switch inside the TB, or does it remain in the inlet tract when the
TB is removed.
Click to expand...



When I did this on a '79 240 I found it was easier to remove the intake
manifold, though you should replace the gasket if you do that. There's also
a gasket between the TB and the manifold that should probably be replaced
but if you're careful you can reuse it if you have to.
 
On your Fuel system there is no throttle body as in a
LH car what would have to be done is either remove the
rubber boot that goes in between the Intake Manifold &
the throttle unit or as others have suggested remove
the intake manifold
 
G Klein said:
On your Fuel system there is no throttle body as in a
LH car what would have to be done is either remove the
rubber boot that goes in between the Intake Manifold &
the throttle unit or as others have suggested remove
the intake manifold
Click to expand...

Sure there is, in fact it's the exact same throttle body LH Jet uses, it's
just mounted on a different manifold.
 
James said:
Weird, that's the first time I've seen that setup, looks almost like an '81
or earlier 240 except for the distributor on the back of the head. Was KJet
cheaper than LH Jet or something?
Click to expand...

K-Jet is cheaper, and simpler, so there's less to go wrong. However
it's not as precise, so emissions are higher. It was always used on the
normally aspirated 8 valve "E" engines.
 
Mike F said:
K-Jet is cheaper, and simpler, so there's less to go wrong. However
it's not as precise, so emissions are higher. It was always used on the
normally aspirated 8 valve "E" engines.

--
Click to expand...
Perhaps less to go wrong, but what can go wrong seems to do so more often. I
know some have had great luck with KJet but for me it's been nothing but
hassle, LH Jet always seems to run perfectly and when it doesn't the problem
is generally pretty obvious and easily diagnosed.
 
James said:
Perhaps less to go wrong, but what can go wrong seems to do so more often. I
know some have had great luck with KJet but for me it's been nothing but
hassle, LH Jet always seems to run perfectly and when it doesn't the problem
is generally pretty obvious and easily diagnosed.
Click to expand...

Sitting for a long time without use is hard on K-Jet, because of the
accurately machined steel parts in the fuel distributor. Other than
that the only part that really fails is the warmup regulator, and
sometimes injectors. It's biggest flaw is how it reacts to vacuum leaks
though.
 
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