|
|
|
I'm getting frustrated.
Two weeks ago, I broke down 2h from home. I got towed and the guy said it overheated and the engine was shot. I had blown the plastic side of the radiator. Replace the engine with a 90K miles one... $3800!!!.... NOT
I could also sell it to the junk yard for... $350!!!... NOT neither
I towed it myself back home and started to look at it.
Extend of the damages: blown radiator, blown head gasket, and melted plug wires.
I replaced them all over the last few days and it runs great again.
However, it overheats! I removed the thermostat because the old one was cracked, I checked the water pump and it's fine. I even replaced a slightly leaking heater core. and it still overheats!!!
can it be that I cannot run without a thermostat?
I don't think the block is cracked because it's not smoking and there is no evidance of water in the oil.
HELP!!!!!!!! I'm going nuts and my wife is bitching about the car every day for the last two weeks!
|
|
-
posted by
someone claiming to be don
on
Sun Aug 15 10:40 CST 2004 [ RELATED]
|
|
Hi, ive had problems like this before, probably the water pump not circulating the water, or blown head gasket putting pressure in cooling sys.
Is the radiator new or used? could be clogged.
Most likely circulation problem.
|
|
-
|
|
|
I have heard that some engine cooling designs need the restriction of the thermostat in place to keep the internal water flows, pressures, etc at the right levels.
Certainly I would try putting a thermostat in there to see if it fixes your problem. Compared to the work you have done, a thermostat is cheap.
John
|
|
-
posted by
someone claiming to be Aaron
on
Fri Aug 13 22:10 CST 2004 [ RELATED]
|
|
The only way to tell if the thermostat is working or not is to run the car with radiator cap off. At normal operation thermostat will open at certain temperature, if not you will see the coolant starts boiling and coming out from cap hole. If it works correctly, you will see coolant coming from small hose top of thermostat housing to coolant resivour. Make sure not to fill coolant resivour all the way to top.
I don't see anything wrong driving without thermostat. I did that when my thermostat was stuck. Removed it and drove if till I replaced it.
If it's still overheating without the thermostat, something must clogged up somewhere, I'm guessing.
Aaron
|
|
-
|
|
|
I think you're right. It is probably clugged in the engine block. the old radiator blew up at the plastic connector for the top hose (thermostat) which makes me think that the pressure built up too much as the pump was pushing water that was blocked down the road.
when I tested the system, the pressure in that hose would build up. the bottom hose would stay cool much longer than the top one too.
if this is the problem, does anyone know how to flush/blow debris out of the block (I'm guessing that's where the problem is)?
|
|
-
posted by
someone claiming to be Aaron
on
Fri Aug 13 14:48 CST 2004 [ RELATED]
|
|
How about the radiator cooling fan? Does it work? Loose any coolant? I had overheat problem with loss of coolant. Finally found that hose fitting at the bottom of coolant resivour was crack.
|
|
-
|
|
|
not loosing coolant, fan works as advertised. it actually kick on right when the gauge show increasing from normal temp.
|
|
-
posted by
someone claiming to be Wolfgang
on
Fri Aug 13 12:44 CST 2004 [ RELATED]
|
|
There is no reason that I can think of why running without a thermostat should cause overheating problems. It is simply a mechanical device that throttles the water flow out of the engine. If you take it out the water will circulate at max rate and cool the engine excessively. So, without the thermostat you would expect the engine to never warm up fully - if everything else in your cooling system is working correctly - and run cold / cool.
If it is overheating without a thermostat, it sounds like you have some other issues. Can you confrm that the water is circulating through the radiator when the engine runs? The hoses to and from the radiator should warm up quickly when you start the engine from cold as the thermostat will not be stopping the flow. One possibility is that one of your radiator hoses has collapsed internally, resulting in a blockage.
Seems a coincidence that the problems started with the car overheating initially. Maybe there is a pre-existing problem that has not been cured by the repairs. I cannot believe there is anything other than a lack of coolant flow or quantity that would result in overheating - presuming that the radiator and cooling fans are working normally.
Wolfgang
Wolfgang
|
|
-
|
|
|
Is the hose that goes from the radiator to the thermostat flowing to the radiator or from? the reason I'm asking is that I noticed this hose gets really hot fast and the bottom one (bottom of the radiator) stays cool for a while. The coolant is circulating in the heater core since it can get toasty fast if I run it full blast.
The reason I was asking about the thermostat is that the expension hose comes from the top of the thermostat housing. I was wondering if a free flowing coolant would interfear with it in some way. I don't know what to think anymore. I removed all the rubber hoses when I was doing the head gasket so I don't think that would be it.
I'm just very confused right now...
|
|
-
|
|
|
N Sabardin,
The flow is from the thermostat to the radiator top. The pump is centrifugal and does not build up huge pressures. The pressure in the system is primarily from the water heating. Because the pump requires free flow to work, some checks you can make with engine off are;
1. Disconnect top and bottom radiator hoses. Do not connect directly to water line pressure for fear of blowing radiator, but water should flow freely through the radiator, in the top hose(disconnected at the thermostat) and out the bottom in good volume. I picture a hose nozzle loosely held in the hose at top for this test.
2.You could have a collapsed inner hose or hose obstruction, or (less likely) an obstruction in the engine. Take out the thermostat and try running water thru the engine and both hoses. Water in the top hose, through the engine and out the bottom hose (and pipe too if possible to disconnect it at the engine). It should flow freely without the thermostat. Clamp off a heater hose for this test to ensure you are flowing thru the block.
The fact that the heater works does imply that the pump is working. I don't think the expansion hose from the thermostat housing is an issue.
|
|
-
|
|
|
I'll try that.
one question: should I test the engine block through the thermostat housing or the expension tank filling house (as opposed to the overflow hose)? an should I clamp anyone of these hoses when testing (in addition to the heater hoses)?
thanks
|
|
-
|
|
|
Your idea to go in the tank lower hose sounds good. You should clamp off the lower radiator hose to force the water thru the engine. Clamp the overflow hose and go in thru the tank cap for a first try. That should give you a pretty good idea without disconnecting the pipe or lower hose. I'd try flow both ways just for fun, in thru the thermostat hose and out the tank hose too. In order to check the metal pipe, and lower hose, you should remove the lower hose clamp and flush thru the tank and the water should come out the radiator top hose.
|
|
-
|
|
|
Some update:
I flushed the whole system. stuck my garden hose in the radiator, the thermostat housing, and the engine water intake hose as well as the expension tank hoses. they all flow freely. I even ran the engine with the garden hose in the engine water intake hose and it would come out the thermostat housing with great force, so I know (if I wasn't already convinced) that the water pump works good.
I went for a test drive and it all went well for quite some time but then... it happened again. all the sudden and for no apparent reason, it shot towards the red, went back down for a while then up again.
I made it home and touched the top hose... boiling hot... bottom hose... barely warm! clogged again! I can only think of one thing. the bottom hose is weak and it must be collapsing on itself under the engine suction. I had removed it and ran the garden hose in it but it was working fine then.
I'll get a new one on monday and see what happens.
|
|
-
posted by
someone claiming to be Wolfgang
on
Sun Aug 15 01:20 CST 2004 [ RELATED]
|
|
Did you have the thermostat out for the test drive? As in the longer term you would need to have one fitted, maybe it is a good idea to slap a new one in now.
I doubt the lower hose would be collapsing under pump suction, as normally the pressure from the hot water would place the whole system under positive pressure, and the pump would circulate the water.
I have had radiator hoses delaminate / tear / collapse internally (not on my 850) so they look OK from the outside but are RS internally. This type of failure can lead to the behaviour you are experiencing.
One thing to be a bit wary of is when you refill your cooling system (with the thermostat in) is that you will often get a substantial draw-down of water when the thermostat first opens, releasing an the lock. It makes sense to fill up, let the engine warm up till the thermostat opens, and then top-up again.
Let us know how you get on!
|
|
-
|
|
|
I think Wolfgang has it. Hose failure. A hole/crack in the inner hose lining would allow water to escape into the space between the inner lining and the outside hose cover. Result-- no external leak and inner hose not supported by pressure (because it has equal pressure on both sides of it) and is free to collapse or otherwise block water flow. BTW, this could occur with EITHER upper or lower hose and is virtually invisible to all flow tests performed. At this point, I would suggest replacing both hoses.
|
|
-
|
|
|
OK, here is where I stand:
I replaced both hoses and the expension tank cap.
the car did OK most of the day but at times it went toward the red and I had to stop then refile the tank a bit. When I went toward the red, I would put the heater on and it would come back to normal temp. I'm still hoping I solved the problem and that today was only the result of air locks working their way out.
More tomorrow...
|
|
-
|
|
|
After now three days since the system was flushed, it still overheats. It's not as bad as before and I can go for 15 minutes without any signes of trouble. Then, it will shoot toward the red. I noticed one thing though: when it starts overheating, if I put the heater on full blast, the temps goes back to normal range right away.
I really don't know what to do anymore. Could it be a crack block? It's not smoking, and it's not mixing with oil.
Could it be a bad sending unit to the gauge?
What a pain in the neck....
|
|
-
posted by
someone claiming to be Wolfgang
on
Wed Aug 18 01:58 CST 2004 [ RELATED]
|
|
Wow, I'm glad it's not me having this trouble!
I must admit that I am losing the plot a bit, as lots of things have changed. Is it right to presume you now have:
(1) New radiator
(2) New top and bottom radiator hoses
(3) New green pressure cap
(4) New heater core
(5) New head gasket
(6) No thermostat
(7) No loss of coolant problems since the head repair
(8) no leakage of oil or combustion gases into the coolant
(9) Cooling fans that always kick in and out on demand
(10) Good water pump delivery
And despite this, you still have overheat problems. You do not say in your message whether the overheating occurs while driving steadily along the highway or whether it only occurs when moving slow or stopped in traffic. The reason I mention this is that at reasonable speed, the natural airflow thru the radiator should be enough to keep things cool without assistance of the fans.
Also, if the temperature is behaving erratically when all other things (like driving conditions, speed, etc) are unchanged, it points to a rather strange or intermittent (or both!) problem.
What I don't understand is whether you have a flow problem or, like you say, you may simply have a problem with your temperature measurement/display system. What is the best way to resolve this? Possibly replacing the sender and checking the integrity of the temperature gauge circuit is one. Maybe this is the next step.
If there is another problem, and it is indeed related to the cooling circuit itself, then it points to some sort of intermittent obstruction to the water flow (or a very badly behaving thermostat if you have one in at the moment).
I struggle to think of what could cause a flow obstruction. It would need to be something in the water circuit that occasionally "gets in the way". Is it a coincidence that this problem has only appeared after the intial radiator/head gasket problem? I know it is a long shot, but is it possible that here is something rattlng around in the outlet tank of the new radiator that occasionally partially blocks the outlet?
Hey, I seem to be asking more questions than offering answers, but it is a real puzzle.
Wolfgang
|
|
-
|
|
|
I have a new thermostat.
I have no leak but I noticed that one of the heater core returns (at the firewall) was corroded a little from a potential small (and old) leak.
I have been putting coolant back a little after the hose replacement. Could still be burping from the flush.
I'm not sure how to check for combustion gas into the coolant but I would assume that if the gas can pass through, the coolant could pass through too in the cylinders and I would smoke.
The overheat happens really fast, in a matter of 5 seconds.
It can happen on the highway or at slow speed. It seems and (I stress "seems") that it happens after about 15 minutes of constant driving (or maybe engine running)
It really reads on the gauge like if it is blocking somewhere but I can't understand why turning the heater on fixes at least partially the problem (it prevents it from going in the red but it still might be above normal temp)
I'll try a new temp sending unit. At this point I might as well....
|
|
-
posted by
someone claiming to be Wolfgang
on
Wed Aug 18 03:38 CST 2004 [ RELATED]
|
|
Based on what you describe, I would be looking at the temperature sender or some part of this circuit. It is my understanding that the sender feeds into one of the computers and there is not necessarily a linear relationship between temperature and indication on the dasboard display. If the sensor has become unstable and overly temperature sensitive, then this could be a cause.
Unfortunately, I cannot comment on what else could be wrong with the temperatre measurement circuit that could cause this type of response.
I wish I was more confident about this, but if I were in your shoes I would be looking at this next. One reason to suspect something in the measurement circuit is that I struggle to think of a way that the temperature could really increase so rapidly (ie in 5 seconds).
If the sensor has gone silly, it is possible that you are getting the response you see when running the cabin heater flat out as this pulls heat directly out of the water in the block, so the water presented to the sensor is marginally cooler and therfore the sensor reverts to a more normal reading. However, one could present a number of flaws in this logic, unfortunately.
If you had a portable digital temperature indicator, it would be possible to strap a thermocouple on somewhere near the sensor (thermostat cover?) and correlate indicated temperature to a real independant measurement.
Wolfgang
|
|
-
|
|
|
I don't think it's the temp sender. It overheated again.
I have identified now that it is really overheating as the cap of the expension tank is spitting overflow when it overheats.
Also, it doesn't overheat unless I start getting into higher RPM (3500+) for a certain period (not just acceleration) like on highways or if I downshift.
I don't know what to do anymore so I'm going to get the whole system professionally flushed and refilled.
Wish me luck!
|
|
-
|
|
|
Another possibility at this point: Head gasket leaking combustion chamber pressure into water jacket. This could be what is blowing thru the cap and the overheating could come from the water pump filling with combustion gas and not pumping.
If it only fails on the road, you need to find a shop which has a detector which can sense exhaust gas in your overflow tank. You could also, cold or hot engine, crank it over with the ignition coil disconnected and look for air bubbling into the overflow tank. Good LUCK!!!!!!!
|
|
-
posted by
someone claiming to be Wolfgang
on
Thu Aug 19 00:37 CST 2004 [ RELATED]
|
|
Good point. I have neve had it done, but understand that sniffing for combusition products is SOP.
Another thought is a pressure test on the cooling system, with the engine both cold and hot. A good chance if there is a crack, this would be evident as slow leakdown on the coolant system pressure.
Maybe it is a part of an overall system check-over of the coolant syatem, ie pressure test, flush, operational check, gas detection.
It also comes back to the problem that started this all off - ie blown head gasket and ruptured radiator tank. There is a distinct possibility that there is an underlying issue with the block/head that only becomes apparent under certain conditions.
Wolfgang
|
|
-
|
|
|
Guys, I want to thank you all for your help. I finally got the car fixed.
Your blow-by theory was correct. I went and check my compression and the seal did not hold. I had to take the head out again and bring it to the shop to get flattened. Put it back and all is well now. You could actually see where the blow-by was on the head gasket.
Cost me a second head gasket, headbolts, exhaust and intake manifolds gaskets but hey... plus I'm getting really good at setting the timing belt on ;)
Thanks again.
Nick
|
|
-
posted by
someone claiming to be Wolfgang
on
Mon Aug 23 00:14 CST 2004 [ RELATED]
|
|
Nick
Congratulations on your preseverence. Hopefully your faith in the cooling system is restored and it remains trouble free from here on.
Wolfgang
|
|
|
|
|
