Vacuum pipes to break booster

UkCarlos

New Member
Joined
Dec 17, 2009
Messages
5
Reaction score
1
Location
Sheffield
I have a 2004 2.8crd automatic and have recently started having issues with the brakes, whereas the pedal acts normal but periodically it goes hard. I’ve checked the valve on the booster and it appears fine as is the vacuum from the engine but for some reason there’s another narrower pipe leading off the check valve and at the moment I cannot figure where this goes and should this also have a vacuum, as at the moment it doesn’t?
As these Jeeps are becoming rare in the UK, I’m struggling to solve this problem, anybody got any ideas?
 

Billwill

Full Access Member
Joined
Nov 26, 2009
Messages
2,000
Reaction score
457
Location
White River, South Africa
The CRDs get their brake vacuum from the Vacuum Pump whereas the Gassers get it from the Intake Manifold.

The rubber pipe from the Vacuum Pump goes up to the Brake Booster and has a branch going into the cabin to drive the interior vents ie. directs where the airflow goes...feet, side vents, demister.

Check if all these vents work correctly...if the vacuum pipe to the cabin has come off or is torn then the air will only come from the demister vents....this may affect the Brake Booster vacuum!

If that is not the problem then there may be a problem with your Brake Booster and I have heard of a few problems with the Vacuum Pump starting to fail....it has carbon vanes that can wear out but this is not common.

My 2002 Export 2.5L CRD has had one problem in this area..years ago the Dealers knocked off the vacuum pipe to the interior so I only had air-flow to the demisters.:(

Do you have the Service Manuals for your Jeep?

You can download them here..2004 is not covered but the 2003 will be close enough!

But very important is to download the section marked:

"2_5 2_8 export diesel" as it has information specific to these old Export Diesels of ours...there is one section that lists the Error Codes and tell you what to do about them!;)

The Error Codes cannot be pulled out by any scanners other than the Dealers' OBDIII Scanner as the early KJs use a PCI bus.

There is a way to pull the codes out using a "Key" method...get back to me if you need to know how to do this!

www.colorado4wheel.com/manuals/Jeep/KJ/
 
Last edited:

UkCarlos

New Member
Joined
Dec 17, 2009
Messages
5
Reaction score
1
Location
Sheffield
The CRDs get their brake vacuum from the Vacuum Pump whereas the Gassers get it from the Intake Manifold.

The rubber pipe from the Vacuum Pump goes up to the Brake Booster and has a branch going into the cabin to drive the interior vents ie. directs where the airflow goes...feet, side vents, demister.

Check if all these vents work correctly...if the vacuum pipe to the cabin has come off or is torn then the air will only come from the demister vents....this may affect the Brake Booster vacuum!

If that is not the problem then there may be a problem with your Brake Booster and I have heard of a few problems with the Vacuum Pump starting to fail....it has carbon vanes that can wear out but this is not common.

My 2002 Export 2.5L CRD has no problems in this area..years ago the Dealers knocked off the vacuum pipe to the interior so I only had air-flow to the demisters.:(

Do you have the Service Manuals for your Jeep?

You can download them here..2004 is not covered but the 2003 will be close enough!

But very important is to download the section marked:

"2_5 2_8 export diesel" as it has information specific to these old Export Diesels of ours...there is one section that lists the Error Codes and tell you what to do about them!;)

The Error Codes cannot be pulled out by any scanners other than the Dealers' OBDIII Scanner as the early KJs use a PCI bus.

There is a way to pull the codes out using a "Key" method...get back to me if you need to know how to do this!

www.colorado4wheel.com/manuals/Jeep/KJ/
Thank you so much for your reply, it is very much appreciated.
I do have an issue with the interior vents exactly as you have described and I had looked at the vacuum hoses that go into the check valve on the brake booster and did a test to see if there was any vacuum coming from the engine - basically I put my thumb over the tube!
The branch tube has a connection piece which I’m assuming maybe another check valve that then branches off into the cabin. I’ve not actually got to this as it all seems to be under the coolant tank and I didn’t at this stage want to disturb this. I did figure out a hose comes from that branch to the boost solenoid that activates the egr unit - the one with RHD paper air filter attached at the bottom - and I was wondering if this could be faulty but the car runs really well and idles perfectly..
One other thing I have noticed though is if you accelerate hard, say up a hill, then take your foot completely off the accelerator pedal there is a “fluttering” noise - sorry difficult to describe this in text but if you purse you lips and **** in short bursts it’s something like that
I’m wondering now if it could be the vacuum pump that’s at fault. To be honest the “fluttering” noise has been on the car for a while and I was told it was the engine turbo releasing pressure, the spasmodic hard brake pedal is a recent thing and although I’ve changed the discs, pads and rear brake shoes, it’s still suffering from this - can be a bit nervous when driving, especially in the UK with nose to tail traffic!
The one thing I didn’t change was the brake lines to each wheel and even though the system was bled I’ve noticed a bit of discolouration in the reservoir so I’ll look at doing this at some point in the near future.
I’ve finally managed to track down a service manual - which arrived yesterday- but thank you so much for the link
If you could however educate me regarding the “key” method, I’d appreciate that.
 

Billwill

Full Access Member
Joined
Nov 26, 2009
Messages
2,000
Reaction score
457
Location
White River, South Africa
I hope the Service Manual you got hold of caters for the Diesel engine...the USA/Canada only got Diesels in 2005. If not...download the manuals I listed!;)

A good site to go to for these Export CRDs of ours is the Aussie site

www.ausjeepoffroad.com

They have identical KJs to what you and I have so can supply some good advice....go to the KJ section!

The vacuum pump sits behind the cover on the front of the engine.
If you had this cover removed then looking at the front of the engine this pump sits at about 2 O' Clock so you should be able to feel around that area for the pipes coming of the pump.

I have not worked in that area but some CRD Owners here should be able to advise you where the vacuum pipe goes once it leaves the pump and splits up to go to the Brake Booster and inside the cabin for the air vent control.;)
 
Last edited:

Billwill

Full Access Member
Joined
Nov 26, 2009
Messages
2,000
Reaction score
457
Location
White River, South Africa
As regards the "key" trick to pull out codes.

Without starting the engine, rapidly turn the Ignition key ON/OFF 4 times. After the 4th ON/OFF action leave the ignition ON.
The Odometer Display should start displaying the Error Codes in sequence from the oldest to the latest codes...write them down!

You cannot erase the codes, any code will only show once even if it has occurred several times. The oldest codes may no longer be relevant anymore....concentrate on the last few codes written down!

Export models seem to like turning the key ON/OFF 4 times...USA/Canada models seem to like 3 times!

Then you must have downloaded the "2_5 2_8 export diesel" manual I told you about....this has the error codes and tells you what to do about them. Sometimes the flow charts will tell you to check voltages,
continuity etc. which you can do but when it calls for the DBIII tool that is far as it goes...only the Dealers have this.

Write down the last codes for us so we can see what the status is at the moment!;)

As far as brake fluid is concerned...I take a large Syringe with some tubing attached and **** out as much brake fluid from the Brake Reservoir as I can then top up with new fluid..I do this about every second year. My 2002 Export model takes Dot 3 brake fluid but you can probably use Dot 4. I do the same with my clutch reservoir using Dot 3. I do the same with the Power Steering Fluid...my 2002 uses Mopar Steering fluid which is almost clear...your 2004 should use Red ATF +4 fluid.;)
 
Last edited:

UkCarlos

New Member
Joined
Dec 17, 2009
Messages
5
Reaction score
1
Location
Sheffield
As regards the "key" trick to pull out codes.

Without starting the engine, rapidly turn the Ignition key ON/OFF 4 times. After the 4th ON/OFF action leave the ignition ON.
The Odometer Display should start displaying the Error Codes in sequence from the oldest to the latest codes...write them down!

You cannot erase the codes, any code will only show once even if it has occurred several times. The oldest codes may no longer be relevant anymore....concentrate on the last few codes written down!

Export models seem to like turning the key ON/OFF 4 times...USA/Canada models seem to like 3 times!

Then you must have downloaded the "2_5 2_8 export diesel" manual I told you about....this has the error codes and tells you what to do about them. Sometimes the flow charts will tell you to check voltages,
continuity etc. which you can do but when it calls for the DBIII tool that is far as it goes...only the Dealers have this.

Write down the last codes for us so we can see what the status is at the moment!;)

As far as brake fluid is concerned...I take a large Syringe with some tubing attached and **** out as much brake fluid from the Brake Reservoir as I can then top up with new fluid..I do this about every second year. My 2002 Export model takes Dot 3 brake fluid but you can probably use Dot 4. I do the same with my clutch reservoir using Dot 3. I do the same with the Power Steering Fluid...my 2002 uses Mopar Steering fluid which is almost clear...your 2004 should use Red ATF +4 fluid.;)

Hi Billwill,
Belated update on my vacuum issue.
All the vacuum pipes - servo- and check valves have been tested and all appear fine. The brake fluid was flushed out and replaced at the same time.
The next thing I looked at and subsequently changed was the booster solenoid - I replaced this with a second hand part - which along with an after market small filter, has actually cured the issue!
I’ve enquired about getting a new part but as all Jeep sales go through Fiat dealers in the U.K. they receive parts from Italy and to be honest, I was quoted a three week delivery at a cost of £169.00. I’ve since sourced the part - Mercedes- along with the small paper filter from eBay for £45.00 and will keep it as a spare as the Jeep is running really well at the moment. I checked out all the engine codes with a scanner and it was free of anything - apparently vacuum issues don’t register?
Again thank you so much for your help
 

Billwill

Full Access Member
Joined
Nov 26, 2009
Messages
2,000
Reaction score
457
Location
White River, South Africa
Glad you fixed it...nice that you can obtain a Scanner that reads CEL codes out. The 2002 models...at least the CRDs...cannot use any scanner other than the Dealers OBDIII scanner as the PCI Bus used on the early CRDs is not supported by any scanners.:confused:

If you electrically disconnect the solenoid you will probably get a CEL code...try unplug it to see if it posts a code.!
 
Last edited:

J.C.

New Member
Joined
Jul 30, 2015
Messages
14
Reaction score
0
Location
Townsville, Australia
Hi Billwill,
Belated update on my vacuum issue.
All the vacuum pipes - servo- and check valves have been tested and all appear fine. The brake fluid was flushed out and replaced at the same time.
The next thing I looked at and subsequently changed was the booster solenoid - I replaced this with a second hand part - which along with an after market small filter, has actually cured the issue!
I’ve enquired about getting a new part but as all Jeep sales go through Fiat dealers in the U.K. they receive parts from Italy and to be honest, I was quoted a three week delivery at a cost of £169.00. I’ve since sourced the part - Mercedes- along with the small paper filter from eBay for £45.00 and will keep it as a spare as the Jeep is running really well at the moment. I checked out all the engine codes with a scanner and it was free of anything - apparently vacuum issues don’t register?
Again thank you so much for your help
Hello Carlos

I have a 2007 RHD Export KJ Cherokee CRD LTD and am getting the same symptoms with mine.

What is the OEM part number of the "booster solenoid" that you replaced?
Can you also give me some more information on the "after market small filter" that you used, please?

Regards
John
 

UkCarlos

New Member
Joined
Dec 17, 2009
Messages
5
Reaction score
1
Location
Sheffield
Hello Carlos

I have a 2007 RHD Export KJ Cherokee CRD LTD and am getting the same symptoms with mine.

What is the OEM part number of the "booster solenoid" that you replaced?
Can you also give me some more information on the "after market small filter" that you used, please?

Regards
John
Hi John,
I managed to get both parts off eBay and they a Mercedes Benz - sprinter - part.
Hello Carlos

I have a 2007 RHD Export KJ Cherokee CRD LTD and am getting the same symptoms with mine.

What is the OEM part number of the "booster solenoid" that you replaced?
Can you also give me some more information on the "after market small filter" that you used, please?

Regards
John
Hi John,
I managed to get both genuine replacements in the end as both parts are used on Mercedes Sprinter engines.
I bought the turbo boost pressure converter off eBay for around £20.00
The little replacement filter called a control valve intake is a Febi Bilstein part 39393 again off eBay @ £16.85.
Incidentally, the Jeep now has a aftermarket electric brake vacuum pump which has made it a lot more efficient. The engine just runs the heating and ventilation side.
I hope this helps?
Cheers
 

J.C.

New Member
Joined
Jul 30, 2015
Messages
14
Reaction score
0
Location
Townsville, Australia
Hi John,
I managed to get both parts off eBay and they a Mercedes Benz - sprinter - part.

Hi John,
I managed to get both genuine replacements in the end as both parts are used on Mercedes Sprinter engines.
I bought the turbo boost pressure converter off eBay for around £20.00
The little replacement filter called a control valve intake is a Febi Bilstein part 39393 again off eBay @ £16.85.
Incidentally, the Jeep now has a aftermarket electric brake vacuum pump which has made it a lot more efficient. The engine just runs the heating and ventilation side.
I hope this helps?
Cheers
Have you got any information on the brand and specifications of your new electric brake vacuum pump, that you can share?
 

UkCarlos

New Member
Joined
Dec 17, 2009
Messages
5
Reaction score
1
Location
Sheffield
Hi John,

Apologies for the belated reply. I got a local garage to fix this in the end and he supplied the parts but basically it’s an electric vacuum pump that’s positioned behind the battery with the power going into the front engine fuse box. The vacuum pipe goes straight to the brake booster with a solenoid switch which activates as required - it doesn’t run all the time.

it’s relatively quiet - cannot be heard over the CRD anyway - and has definitely improved the braking performance.
The original vacuum pipe from the engine is only connected to the egr solenoid and the hvac system.

Including the part and labour, it cost me around £350.00 which was a far cheaper option to keeping the Jeep going then trying to replace the integral vacuum pump, which now just generates enough to run the solenoid and hvac.

My Jeep is a RHD 2004 2.8 CRD Automatic LTD
150 bhp.

I hope this helps.
 

Latest posts

Members online

Top