I am trying to track down a possible vacuum issue. I have no HVAC
control and understand it is operated by vacuum.
I found what looks to be a vacuum line disconnected on the driver side
of the motor but can not find where it goes.
I bought this S10 ZR2 4X4 for short money and am just getting it ready
for the winter. It had a recent motor swap and I believe a few things
might have been re-connected. Also the 4X4 does not engage. Could this
be a vacuum issue also? Thanks
Yep, Same vacuum feed is used by both systems. The line on the 98 comes
from the engine to a T near the left hood hinge area. Then one line runs
up to the vacuum reservoir and the other feeds the control systems.
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That does sound like the line I have that is dis-connected.
Can you tell me where exactly on the engine does it go.
I have looked all over the manifold and can not find the source.
The line only reaches around the rear quarter of the engine.
Look under the upper radiator hose on the left side of the engine next
to the throttle body plenum for a fitting that twists into the intake
manifold. The connection is there if this is a 96 or up engine. If you
cannot find one there any continuous manifold vacuum source will work.
This issue is getting a bit ridiculous. I took the truck to a local
mechanic. He couldn't find the vacuum source also.
He called Chevrolet for help. No luck there also. Finally he contacted
a customer with a similar vehile (99 S10 Blazer) that he is going to
examine today to find where the vacuum hose is coming from on that.
Hopefully it is the same.
This might seem unusual, But I'm getting used to the statement: "In
all my years doing this, I've never come across anything like this".
OK All squared away finally. We found that the vacuum source is at the
plug from the PCV valve on the manifold. Aparently the plug used for
a 2WD vehicle is different than on a 4WD. I found a 4WD GMC at a
boneyard that has the port for the vacuum line and swapped it out.
I went back and read what you wrote as to where it was located. You
were right Steve. Now I have another issue. I brought the truck to
Jiffy Lube Saturday. They told me I have 2 Oil Filters and they could
only get to the front one. I haven't figured out why there is another
one and where it is exactly.I do have an S10 Manual to look through. I
am sure it has to do with the 2WD motor in the 4WD truck again. There
must be a way to eliminate one of them?
I'm starting to wonder how much that 2000 boneyard 4WD motor is and
what it will take to swap that one.
The two wheel drive engine has a conventional filter mount located on
the side of the block. BUT in order to fit the engine into a 4X4 chassis
and be able to change the filter they used a remote kit that moved the
filter up to the front of the vehicle behind a panel. Installing that
adapter eliminates the rear mounted filter. Now IF the person did the
swap using factory parts this is how the they would have done it.
However it is possible they used a couple different pieces from the
different vehicles. If the 2WD had an oil cooler they may have used the
4WD oil cooler lines and filter with the 2wd adapter on the engine. That
would give you two filters. Kind of dopey but it could be.
You will be able to see the extra filter from under the hood. Just look
down below the steering shaft between the engine and the frame rail. The
filter will be visible and so will the oil cooler lines.
Other than a few minor exterior items the engines are the same
regardless if they are rwd or 4X4. The later versions do have more power
and some nice features internally though.
I'll check and see where/if the remote oil filter goes.
If it's not connected then they put a new oil filter on for no reason
and the old oil filter is doing the filtering. I imagine the same oil
filter is used in both locations?
I can drop the skid plate and change the filter myself if need be.
When I got the truck the skid plates were off it. I put them on.
Thanks again Steve
Different filter is used. They are the same base size BUT the 4X4 filter
It is possible that both are connected. The easy solution if that is the
case is to buy the proper filter adapter for the 4X4 and bolt it in
place. Only takes about 20 minutes to do if needed. Basically you would
disconnect the oil line (one bolt in the center), then remove the
filter. Unbolt the adapter on t=it (two bolts) clean the block face and
install the new adapter with the proper gaskets. Then reconnect the oil
lines with new O rings on them. Should be less than 50 bucks for
I got the complete vacuum line run diagram from my local GM parts
department. he printed it off and faxed it to me. It too a while
because he did not know where to find it in the computer. I think he
found it under the 4 wheel drive / HVAC are of the manual. My truck
had a similar broken line up on the driver side near the fender. My
vents didn't move and my 4X4 didn't engage. I found the leak and
plugged it witha screw. Unfortunately the line needs to be connected
to the "vacuum ball" or "vacuum canister" this acts a a surge vaccum
tank. Without it my 4 wheel drive would kick out whenever I put a load
on the motor. Based on the diagram I have it appears the hose is about
10 inches in total length, The down side is I still can't tell how to
get to the cannister as it is mounted between the inner and outer
That one is a PIA, you either remove the inner fender to get to the
canister, OR you can replace it with one from a junk yard. The 95-98 had
them mounted under the hood, as did some others. Just connect up that
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