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Folks with good mechanical experience please chime in.

maxtdi

Go Kart Champion
Location
Nor-Cal
Car in question
1998 Crown Victoria
347k miles
Original engine + transmission
Newish T stat (<100k miles)
Newish Radiator (<100k miles)
Doesn't lose/leak coolant
Doesn't lose/leak oil
Oem waterpump
No misfires etc, idles smoother than my car or most others
No check engine lights

1. Problem #1.
Intermittent overheating.
Car suddenly goes up in temperature, from normal to almost at the end of the temp gauge, gives warning. Pull over- Let car rest and then its fine This happens when cold out (18f yesterday) or when hot or with or without AC. So that should rule out a fan issue. This happens once every other month or so. So it is incredibly hard to reproduce.

2. Problem #2.
Intermittent ABS engagement.
Only on low speed (<5mph) right hand turns during light braking the car feels like it engages the ABS and the pedal pulses. It can get kind of scary because it significantly increases stopping distances.
(ABS warning light not on)

Any ideas with how to quickly/cheaply diagnose/fix these issues?
 

Jaber

Modero
Location
Iowa, IL
#1, my bet was going to be T-stat, but you listed as recently replaced. Although it's possible it could still be bad and it's not opening/closing properly. Try touching the lower/upper radiator hose to see if there's a temp difference? If there is, coolant isn't flowing. Was the T-stat/Radiator replaced for this problem? I'm assuming you ruled out fan, by visually confirming it's turning on when you have heater on and car is close to overheating?

Other guess would be there's air getting into the system. Do the belts make any noise?
 

maxtdi

Go Kart Champion
Location
Nor-Cal
#1, my bet was going to be T-stat, but you listed as recently replaced. Although it's possible it could still be bad and it's not opening/closing properly. Try touching the lower/upper radiator hose to see if there's a temp difference? If there is, coolant isn't flowing. Was the T-stat/Radiator replaced for this problem? I'm assuming you ruled out fan, by visually confirming it's turning on when you have heater on and car is close to overheating?

Other guess would be there's air getting into the system. Do the belts make any noise?

All good guesses... I went with the same line of thinking.

1. A sticky T stat would likely cause more of an issue than I am seeing now, my problem seems far too intermittent. And yes both hoses get hot etc.

2. Radiator developed a small weep after 270k miles so I replaced it preventatively.

3. Intake manifold was replaced at around 300k miles due to design flaw, it comes with a fresh T stat. Never had an issue before/after until now.

4. Fan turns on when i turn AC on so it seems to be functioning properly. They tend to be on/off switch like so I doubt that is an issue. Usually a failing fan will show itself at low speeds or in hot weather when the car isn't getting enough air. This wasn't the case here.

5. The air in the system sounds like the most likely candidate... I am not 100% sure of how to check for that however.
 

maxtdi

Go Kart Champion
Location
Nor-Cal
#2 Could be the ABS wheel sensor needing cleaning

That is my next step.

Could a malfunctioning rear sensor cause the front ABS to engage? The rear axles got replaced... last time the forgot to use the correct axles with the exciter rings and it ran an ABS code... but that sprang a code.

This time around I am not 100% if that could be causing the issue.
 

maxtdi

Go Kart Champion
Location
Nor-Cal
You might need to elevate the front of the car to clear all the air in the 4.6 cooling system.

Could you tell me more about this? Do I just undo the cross over plug and run the car while it is at an angle?
 

PetrolHead

When's the next track day
Location
Motor City
Car(s)
MKVI GTI
How is the fan triggered when A/C isn't on? Does the ECU turn it on or is there a coolant temp sensor that triggers it, or something else? Since the problem is so intermittent, I highly doubt it's air or the thermostat. If air were in the system, it would likely be a more common problem, same goes for the thermostat. If there's a coolant temp sensor triggering the fan, that could be to blame.

Also, a dirty ABS sensor would cause the ABS problem you're explaining, or the ABS controller. When turning, the wheels are moving at different speeds, which could make the ABS think it needs to intervene. :iono:
 

maxtdi

Go Kart Champion
Location
Nor-Cal
How is the fan triggered when A/C isn't on? Does the ECU turn it on or is there a coolant temp sensor that triggers it, or something else? Since the problem is so intermittent, I highly doubt it's air or the thermostat. If air were in the system, it would likely be a more common problem, same goes for the thermostat. If there's a coolant temp sensor triggering the fan, that could be to blame.

Also, a dirty ABS sensor would cause the ABS problem you're explaining, or the ABS controller. When turning, the wheels are moving at different speeds, which could make the ABS think it needs to intervene. :iono:

I would think it would be coolant temp sensor. Hmm how to diagnose that over the other more common issues is how it gets tricky.

Looks like cleaning the abs sensors is step 1. Can i use brakleen or will it damage things ?
 
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PetrolHead

When's the next track day
Location
Motor City
Car(s)
MKVI GTI
Well, coolant temp sensors are cheap, and depending on location, not too tough to replace. And they do go bad. I had one go bad in my CJ7 with LT1 swap, and it had intermittent overheating issues due to the fans randomly not switching on when they were supposed to. I replaced the sensor and all was good.

Last time I had air in the system was on that vehicle, and the bitch overheated reliably. I don't think air creates super intermittent overheating.
 

maxtdi

Go Kart Champion
Location
Nor-Cal
Well, coolant temp sensors are cheap, and depending on location, not too tough to replace. And they do go bad. I had one go bad in my CJ7 with LT1 swap, and it had intermittent overheating issues due to the fans randomly not switching on when they were supposed to. I replaced the sensor and all was good.

Last time I had air in the system was on that vehicle, and the bitch overheated reliably. I don't think air creates super intermittent overheating.

Good call on the coolant temp sensor. I'll research it... apparently there are two one for the gauge and one for the ECU. Dafuq... redundant system is redundant.
 

Thumper

Autocross Champion
Location
Sedalia, MO
Car(s)
2018 Audi TTRS
Car in question
1998 Crown Victoria
347k miles
Original engine + transmission

No one has suggested the best solution.

Crush car, buy new one. ;) :D


On a serious note, for the ABS issue, check the ring if you haven't already for damaged teeth or debris. I wouldn't spray brake-cleen directly on the sensor itself but if it's dirty it should be to hard to clean up.
 

maxtdi

Go Kart Champion
Location
Nor-Cal
No one has suggested the best solution.

Crush car, buy new one. ;) :D


On a serious note, for the ABS issue, check the ring if you haven't already for damaged teeth or debris. I wouldn't spray brake-cleen directly on the sensor itself but if it's dirty it should be to hard to clean up.

Perhaps, but I am not ready to give up just yet. And given how many miles this car sees it is one of the cheapest methods of transport imaginable. The recent hickups however are quite annoying and time consuming.

I'll check for the teeth.
 

mk6medic

Go Kart Champion
No one has suggested the best solution.

Crush car, buy new one. ;) :D

Have you met Max? That is expensive. He not do that,


I was also thinking coolant temp sensor. Would definitely explain the intermittent aspect. Electrical gremlins at work, yo.
 
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