Hello all, unfortunately, I am still dealing with a coolant leak on my 91 Q. Up until lately, it has been little more than an occasional annoyance - an occasional gurgle and a loss of heat from the HVAC at idle, but I need to address it now as I have experienced a slight increase in temp on two occasions of long-term idling/slow traffic. I don't want to risk an overheat, so I am not driving the car until it is fixed. On to the details:
I have noticed a puddle of coolant on the ground after driving the car which seems to be coming from the area around the rear of the passenger side cylinder head. I am assuming the hoses connecting the engine to the heater core are in this area, and as such the most likely suspects, is this correct? I don't believe the core is the problem, as there is no moisture evident in the cabin. Any other ideas?
I know after I remedy the leak that I will need to refill/bleed the system to evacuate any air. I got the procedure to open the heater core valve on a previous post, but it advised to turn the key off after the HVAC displays "43" to fully open the valve. However, won't this cancel out when I restart the engine to move the air up to the now open upper coolant filler port? Needless to say, I'm still a bit confused as to this procedure.
Thanks in advance for any and all input you all can offer.
Coolant Leak - Likely Culprit?
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greg_atlanta
- Posts: 1111
- Joined: Tue Jul 23, 2002 4:37 pm
- Car: 2008 G35 Journey Sedan, silver/black (no sunroof), 1992 Q45 (in a past life)
Coolant that seems to be coming from the back of the motor may be overflowing from the valley between the cylinder banks. Look between the "legs" of the "spider" (plenum) with a flashlight. See liquid? If so, your plenum must come off and the hoses must be replaced. Important to attend to -- overheats are DEADLY to aluminum motors! Be ready for a big bill if you're paying to have it done -- 8 hours labor just to off/on the plenum.
If you hear gurgling in the dashboard, your coolant is very low. Top it off with the "radiator cap" looking thing you see on opening the hood. No special bleeding procedure really necessary if you're using the heater. The HVAC trick is to make sure you flush all the coolant in a change.
As Greg said, use Havoline Orange. No green coolant for your all-aluminum motor. I am now also a convert to distilled water.
Best of luck!
If you hear gurgling in the dashboard, your coolant is very low. Top it off with the "radiator cap" looking thing you see on opening the hood. No special bleeding procedure really necessary if you're using the heater. The HVAC trick is to make sure you flush all the coolant in a change.
As Greg said, use Havoline Orange. No green coolant for your all-aluminum motor. I am now also a convert to distilled water.
Best of luck!
I'll have to check under the plenum when I get home, although I think I would have noticed any water by now. I am quite aware of the dangers of overheating our engines, which is why the car is sidelined until this issue is resolved.
If the plenum hoses are the problem, is there anything particularly difficuly about the plenum removal, or is it just time consuming? Any special tools necessary other than the basics like a good torque wrench? Is the 8 hour figure a real number, or a service book number? I don't trust anyone to work on my car other than myself unless I truly have no other choice, and I am hoping that this is not such a situation.
I'll post my findings in a couple of hours. In the meantime, thanks for the assistance!
If the plenum hoses are the problem, is there anything particularly difficuly about the plenum removal, or is it just time consuming? Any special tools necessary other than the basics like a good torque wrench? Is the 8 hour figure a real number, or a service book number? I don't trust anyone to work on my car other than myself unless I truly have no other choice, and I am hoping that this is not such a situation.
I'll post my findings in a couple of hours. In the meantime, thanks for the assistance!
Well, I went at it this morning, refilled the radiator and bleed the climate control. I am going to keep an eye on the overflow tank to approximate the amount of coolant lost per heat cycle. There was a *tiny* amount of moisture under the plenum after the refill and bleed, but a good amount of coolant was burped from the upper filler port during the bleed, so this may have been a result of this. There is no standing water whatsoever. I will keep an eye on this area to see if I can catch it while it is leaking.
Assuming the under plenum hoses are not the problem, any ideas on other places to look? FWIW, the car is a 91 with 112K. Thanks in advance.
Assuming the under plenum hoses are not the problem, any ideas on other places to look? FWIW, the car is a 91 with 112K. Thanks in advance.
In my backwoods state capital, I don't trust anyone to work on this rare (oddball?) car either. I'm on my own. T3 in Atlanta is the only service organization I feel I might trust to do anything right the first time.
If there's no coolant "in the valley" (there shouldn't be *any*) I suppose we need to return to what could be leaking at the back of the motor. Freeze plugs? There was a thread about that a year or so ago.
When my under-plenum hoses were leaking, the car gave me two heat-cool cycles before -gurgle- I had to add coolant. Now that I've done it, it's a luxury to not have to crack the hood 4x a week.
Plenum removal is labor intensive. Since it's your first time, it may take more than 8 hours round-trip. Go ahead and cut hoses that hold you back -- it will save your sanity and your back. Even DIY, it's possibly expensive, since there's plenty to examine while you have the plenum off, particularly the knock sensors, likely casualties if you're having temp problems. And just as important, the knock-sensor wiring harness, which can corrode if it's been in a damp under-hood environment.
When I bought mine, the "under plenum kit" from Scottsdale did not include the most likely leaky hoses -- the "coolant bypass" hoses. Once you have it off, there's always something else.
A light-duty torque wrench is the only "special" tool you need.
Oh, there's a bracket connected to the driver's side rear of the plenum. The wiring from the driver's side oxygen sensor is tie-wrapped to it. You'll think you have everything disconnected, but then you end up tugging on that poor oxygen-sensor wiring for all it's worth. My oxygen sensors were old, and I assumed I damaged this one, so I went ahead and replaced them both. It was time anyway. See what I mean?
Be aware that if you order oxygen sensors from sparkplug.com, they take three to four weeks. Reliable, but slow. If you have time to plan ahead, the price is worth the wait. They saved me at least $200 for NGK.
If there's no coolant "in the valley" (there shouldn't be *any*) I suppose we need to return to what could be leaking at the back of the motor. Freeze plugs? There was a thread about that a year or so ago.
When my under-plenum hoses were leaking, the car gave me two heat-cool cycles before -gurgle- I had to add coolant. Now that I've done it, it's a luxury to not have to crack the hood 4x a week.
Plenum removal is labor intensive. Since it's your first time, it may take more than 8 hours round-trip. Go ahead and cut hoses that hold you back -- it will save your sanity and your back. Even DIY, it's possibly expensive, since there's plenty to examine while you have the plenum off, particularly the knock sensors, likely casualties if you're having temp problems. And just as important, the knock-sensor wiring harness, which can corrode if it's been in a damp under-hood environment.
When I bought mine, the "under plenum kit" from Scottsdale did not include the most likely leaky hoses -- the "coolant bypass" hoses. Once you have it off, there's always something else.
A light-duty torque wrench is the only "special" tool you need.
Oh, there's a bracket connected to the driver's side rear of the plenum. The wiring from the driver's side oxygen sensor is tie-wrapped to it. You'll think you have everything disconnected, but then you end up tugging on that poor oxygen-sensor wiring for all it's worth. My oxygen sensors were old, and I assumed I damaged this one, so I went ahead and replaced them both. It was time anyway. See what I mean?
Be aware that if you order oxygen sensors from sparkplug.com, they take three to four weeks. Reliable, but slow. If you have time to plan ahead, the price is worth the wait. They saved me at least $200 for NGK.