| Author | Message | ||
     Steve H Unregistered guest |
Can anybody help me figure this out?!?!? Heres the deal, 98 D1 with about 130K, no heat at idle (but plenty at speed) but temp gauge reads normal. Erractic, shortlived overheating while driving. Seems to be no rhyme or reason to it. I also hear the sloshing sound from the heater core. Got a lot of white foamy bubbles in the radiator after reving it up. Not losing any coolant, coolant level is right on. What I have done so far: Re-cored radiator, flushed system, new thermostat (with jiggle pin @ 12 O'clock), compression test (150, 150, 148, 151, 148, 150, 147, 150), Block test (no exhaust gas in coolant). Will not overheat at idle, only while driving. When it overheats revving the engine seems to help it cool off, then it will be fine for a while. Can anyone help??? Heres my theorys now; pinhole leak in system sucking air but not leaking fluid, partially plugged heater core (but where's the bubbles coming from)? | ||
| Willie Joubert (Willie) Advanced member Username: Willie Post Number: 83 Registered: 02-2002 |
Move North, don't need cooling here.... Sounds like a waterpump issue...only thing you have not mentioned. | ||
| Jason Vance (Jason) advanced member Username: Jason Post Number: 272 Registered: 04-2002 |
When the engine has been running for a while (it is warm/hot), slowly release the cap on the expansion tank (use a rag...). Do you get any release of pressure? I had the same issues with intermittent heat and overheating when my coolant was low. Maybe try filling your expansion tank a little past the midline and see if it falls back to the midline. It certainly sounds like you have air trapped somewhere within the system (and it is not good for the water pump). | ||
| Peter J Blatt (Peteb) Member Username: Peteb Post Number: 63 Registered: 10-2002 |
It sounds to me like you've captivated some air in your cooling system, the sloshing in your heater core tells me that there is not enough flow, the occasional over heating, also points to trapped air, i don't know if there are any bleeding ports on engine, but there may be, in older vw 4 cyl, it seems like they like to point nose up to purge system, 1970's mercedes v 8 that were in the convertables had 3- 4 bleed ports on engine to bleed out air, mabey this will help, Good luck oh, yes, just cause the thermostat is new, doesn't mean it's good spring in block, right! Peter. | ||
| Steve H Unregistered guest |
Yeah, I figure theres an air bubble in there somewhere, but how do I get it out? I have run it with the expansion tank cap off for a couple of hours with no relief! I have parked it nose up on an incline and ran it, no luck. Has anyone had a slow failure of a water pump? I always thought it was an all or nothing type thing. I just went out and pressurized the system through the radiator plug to 14psi and no leaks (coolant or pressure). Whats the best way to bleed the air out? | ||
| Mr Man Unregistered guest |
Steve Coolant systems are made to operate with about 15psi pressure(which elevates the boiling point of the coolant by 30F), so there is no chance that air is leaking in. On my RR the is a fill tower in one of the hoses which goes to the heater core. Do Discoveries have this?? If so top up thru the fill tower. Pour dist water in the fill hole until it is full. Also check your ignition timing. If the timing is retarded, the engine will overheat. You may just want to use a non-contact ifrared sensor to measure the actual temp of all the cooling components($99). You can follow the path that the coolant flows thru the system with this temp gun and it will instantly help you find problems. Randall | ||
| Bill K (Bill_k) Member Username: Bill_k Post Number: 144 Registered: 08-2002 |
I've had the bubbling sound in my heater core for about 1.5 years with no problems. You might want to check out your fan clutch. | ||
| Steve H Unregistered guest |
Nope, no fill tower that I am aware of. Hadn't thought about the system working under constant pressure. So where are all these foamy bubbles coming from?? Could the air bubble be trapped at the water pump and the impeller is cavitating? I will check the fan clutch as soon as I get home! Should be kinda hard to spin when cold, and really hard to spin when warm right? Does Sears or someplace like them have the IR pyrometers? Hadn't thought about that. Thanks for the reponses, keep them coming!!! | ||
| Mr Man Unregistered guest |
Sears does have the thermometer part# 34-82288 $99. Other stores may have them for $79. These sensors are very handy when working on a car, and are lots of fun to play with too. My personal feeling about the fan clutch is that a bad one will not cause overheating unless you cooling system is clogged. The clutch should be loose when the engine is cold, and firm when it gets hot under the hood. It should also slip at highway speeds(no way to check that). But here's another twist on diagnosing a fan clutch: While the engine is turned off the silicone inside the clutch settles in the bottom of the clutch, and that causes it to lock up. That is why the fan is so loud and moves so much air on a stone cold engine. After a minute of running the silicone will get in it's proper position. I suppose that it is possible that the water pump is cativating the coolant. Perhaps you could get a rebuilt one and swap them. Is this the original pump? I have 128K on my truck with the original pump, but I am anal about coolant change and have not belt driven fan(which wears out the bearings faster). Randall |
