Car repair – Page 15 – The Jeep Guru

September 28, 2015September 28, 2015

Passat Coolant Leak

Passat coolant leak

For months now I have been struggling to find a coolant leak on my 2000 V6 Passat. The leak has gotten so bad that I can no longer drive the car.

The leak appeared soon after I replaced a cam tensioner. However the leak was on the opposite head than the one I removed. I assumed the leak had something to do with parts that were disturbed by removing the head.

The leak was at the back on the engine dripping off the driver’s side of the bell housing. Access to this area is very limited due to all the stuff that comes in here.

I removed the intake manifold and noticed that the two water lines to the throttle body were cracked. I could not see any holes but I replaced them anyway. This change did not help the leak.

I was finally able to track the source by dusting he entire area with baby powder. With the powder in place, I was able to see where the drip came from. I saw it was from the coolant pipe at the back of the engine; however I was still not sure of the exact spot.

I removed the manifold again and used my brake pressure bleeder to pressurize the system. I attached to one of the tubes that goes to the throttle body and blocked the other one with a plug. So I was able to see the drip coming off the quick connect from the heater hose.

I was able to pull the clip and work the hose off the tube. I tried cleaning it up and brushing the metal part. But it still leaked when pressured up. On closer inspection I found, that the O-ring inside the quick connect was flat and hard. I priced the new lines and decided to give a try at refurbishing this one. I was able to use a pick to pluck out the old O-ring and then match up one from my kit.

I cleaned everything up well and put the line back in place. I pressurized the system again and this time it held. I left for a bit and the pressure was still on the system when I got back.

Not to get it all back together and give it a test drive.

September 21, 2015

Renix no spark

A few weeks ago I went to start up Scuffy my 1988 XJ and it would not start. The starter spun but the motor would not start. A quick check showed no spark.

I suspected a broken wire but I did not see anything obvious. I began with the usual suspects and checked the connection for the CPS and the ground wire by the dip stick. These both seemed fine.

I then went to check the distributor wiring and found a wire pulled out of the plug. I am not sure this was before or after I unplugged the connector to check it.

I decided to then drag the Jeep into the shop for better diagnosis.

I put a scope on the CPS and it read the correct 500mv. However the wire looked in really bad shape so I ordered a new one. I also ordered a new distributor since the wires were falling out of the connector.

When they arrived, I installed them and expected the engine to fire right up. No such luck. I still had no spark. I hooked up a test light and confirmed the injectors were firing so the computer had to be getting its input signals. Just to be sure, I cleaned the C101 connector at the firewall anyway.

I then started to focus on the coil. I removed it from the ignition control module and tested it. It made a spark out of the system. I pulled the ICM and took it to autozone to be tested. The tech seemed to be unfamiliar with the test procedure but he eventually figured it out and declared the unit bad. He happily sold me a replacement.

I installed that and again no spark. I began to suspect a faulty ECM output. I checked the trigger wire which is yellow and could not detect any pulses. I used a test light to simulate the pulse at the ICM and sure enough the coil would fire.

I was really dreading puling the ECM from under the dash because my racing seats and roll cage make access difficult. However, I needed to test continuity of the yellow wire from the ECU to the ICM.

I began on the engine side since it was easier to access. I began pulling off the wiring harness cover and running my hand along the yellow wire. I soon found where it had been chewed in two.

I quickly spliced the wire and the other one near it that was also cut. The Jeep started right up.

I did leaner several things about the Renix system that I did not know before. It has several differences from the Mopar controller I am more familiar with.

The CPS (crank sensor) on the Renix system has two wires while the Mopar has three wires. The Renix CPS generates a voltage due to eh starter teeth passing the sensor on the flywheel. There is a missing tooth where the coil fires.

The Cam position sensor in the distributor has nothing to do with firing the coil. I have trouble wrapping my head aroun dhti sone but it seesm to be true according toe h Renix control manual. The cam sensor signal helps the ECU determine which of the missing teeth is for Cylinder 1. If the compute can’t get a reference signal it just makes up something. If it guesses wrong, the engine will still run just not as well as if it guesses right. So maybe my broken distributor wire explains why sometime my engine would feel off power and others times run fine.

The Renix coil is fired by a transistor pack under the coil. This pack gets a 12V pulse from the computer when it is time to fire the coil. Timing, dwell etc. are all controlled by the ECU.

The Renix injectors get a 12V pulse to fire and use a common ground wire for all six. The opposite is true for the Mopar that feeds all six with 12V and grounds the one that it wants to fire.

August 18, 2015August 18, 2015

DIY Cool Suit

It gets very hot in the race car wearing three layers of nomex and a helmet and gloves. Some smart guy several years ago invented a system that pumps cool water through a shirt to keep a driver cool. Unfortunately they still charge a lot of money for their nice system.

Being cheap – I decided to build my own. As a chemical engineer, I figured I could build a simple heat exchanger.

For the cooler pump, I used a cooler I got at Goodwill. I installed a boat bilge pump form Walmart. I drilled holes in the cooler for the wires to exit and one for the line off the pump. I got clear vinyl tubing from ace hardware and some fittings to reduce to 1/4″ tubing.

Next came the heat exchanger itself. I added a piece of cloth to a t shirt that had passages sewed vertically in it. Then I looped the tubing through. There is about 20 feet of tubing in the shirt.

I added dry breaks from McMaster Carr to the ends of the tubing to reduce the water splashed in the car. #5012K115

It seems to work in the garage. We will see how it works at Barber this weekend.

July 13, 2015August 18, 2015

944 rear shocks

Our Porsche 944 is intended to be a ChumpCar racer. So it has to meet certain rules. One of the controversial rules states that it can’t have adjustable shocks even if it came with them from the factory. We have elected to remove our very nice and expensive Koni racing shocks and swap in some KYB replacements.

The upper mount uses the stock bolt so we will reuse that. It can be accessed by dropping the suspension fully (removing the bottom shock bolt helps) and turning the head of the bolt from inside the wheel well. You will have to hold the nut with an open end wrench while turning the bolt from the wheel well.

The bottom of our Race Konis were mounted on very nice adapters that allowed the use of the spherical rod ends. To remove the adapters, we first had to support the wheel at just the right height to remove pressure from the bolt. Then the mounting bolt could be unscrewed from the adapter. The adapter was them removed from the control arm.

Since we did not have the original bolts to put the bottom of the shock back we started a quest. We measured the threads on the adapter and found they were M14 1.5. We estimated we needed 80mm of bolt. We set off to ACE hardware. They had one. But only in standard grade. I wanted a 10.9. Lowe’s and Home Depot were less helpful.

After some research on the internet we found that the factory bolt is actually 85mm. Porsche no longer sells it but BMW does. We have ordered a pair of part number 07-11-9-914-829 and will try again next weekend to get the bottom of the shock bolted in place. It is a shame to do so much work to make the car handle worse. But that is racing when you try to follow the rules.

Update: got the bolts from the BMW dealer. Also picked up several at pull a part as spares. Drilling the heads for safety wires was easier than I expected.

June 30, 2015June 30, 2015

Adjust Headlights on Suburban

How to adjust the headlights on a 1995 GMC Suburban

The headlight son my GMC Suburban were really foggy and yellow. I am sure I could have cleaned them and gotten new bulbs but I found a good deal on replacement assemblies so I just changed out the whole thing. The first time I drove i the dark however, I realized I needed to align the new headlights. It was not obvious to me how to do it.

You don’t have to remove the grill to adjust the lights but since I had it off anyway, I took a picture to make it more clear how to adjust them.

Fist of all, the two 4mm hex pins that look like adjusters, are not adjusters. They are the pins that hold the light in place. If you remove these pins you can pull the headlight to change a bulb or something. To change the whole housing like I did you have to remove the grill.

The adjusters are hidden deep behind the grill. They have a funky star head on the bolt but I was able to turn it with a 7mm socket. I had the right socket but it would not fit in the access hole. I used a long extension on my nut driver to reach the adjuster bolt.

See the pictures for more info.