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Ok so I have a 2002 pt cruiser that overheated 2 months ago to the point it stalled.
So concerned about blown head gasket I did a compression test all cylinders cold 125 psi.
So changed thermostat. And radiator. It needed a new timing belt due to bad idler pulley so changed water pump as well. New cap. Yes it is looking like I am a parts changer that is why this is driving me nuts.
I pressured tested the system to 17 psi for 1 hour no leak. I then applied vacum for 1 hour no leak. I used the vacuum to fill it. Then started it and used a sealed funnel to top it off. Ran the car to running temp with sealed funnel doing snap throttles occasionally see a bubble coming up. But it tapers off
Then seal it up with new cap
And it still pushes about 1 quart each day out to the overflow. And does not draw it back in. So in 2-3 days the overflow is full and dumps
And radiator is now low on fluid. Any ideas?
I know this is not electrical. However I keep thinking about the head gasket. I have used the chemical test shown in one of the videos. Which was negative.
I have also put my radiator pressure test set on while running the car. And watched the car heat up. It went to about 20 psi. And the needle never bounced just gradually moved up. And back down as car cooled off. The low power fan kicked on at 209 degrees just like it is supposed to. When it did temperature dropped to 190 or so. And pressure dropped to around 15 psi.
I have confirmed both high and low fans work. And temperature sensor works. And fans kick on at appropriate temps.
It seems to me that the vacuum to pull fluid back in does not work.
I have tried bleeding multiple times. So far no luck. I am going to put a mopar themostat in this weekend. And going to do a cylinder leak down test this weekend.
OK so This weekend I am putting in a Mopar thermostat. See if that fixes it. At the same time will do a Cylinder leak down test. As well as redo my pressure tests and vacuum Tests on the cooling system.
On monday I should have a DSO 2 channel scope with proper leads and amp clamp to do a timing test. We will see how that looks. As I have heard some say that if the timing belt is off then it can cause over heating.
Have you had a look at the bottom of the coolant bottle? I often find that what you're describing (coolant in the bottle doesn't move back into the radiator) is frequently due to debris in the bottle or the transfer hose. The coolant can push it's way past, but can't suck back the other way when necessary. I'd also be suspicious of your new cap. I'd try an OE cap before I'd try an OE thermostat.
If you decide to proceed with the leak down, try to do it on a hot engine if at all possible. Based on your observations of the cooling system tester, it really sounds like you don't have a static leak. I've seen them seal cold and leak hot.
I dunno that a mistimed belt can cause overheating? :huh: Any codes? Those 2.4's will usually let you know if the timing is off, either through a code or poor manifold vacuum. Don't get me wrong - I'm all about scoping stuff! But it might be easier/faster to get the upper timing cover back off and recheck the marks.
Recent I had a car in with a similar issue ( BMW 320 diesel) it turned out to be the vacuum breaker valve in the coolant tank wasn't re-admitting air back into the expansion tank as the engine cooled back down.
" We're trying to plug a hole in the universe, what are you doing ?. "
(Walter Bishop Fringe TV show)
I had a Freelander 1 TD4 in that was losing coolant only when used on longer journeys, on local runs it would run for weeks without any loss of coolant but on a 50 mile return trip a litre/quart would vanish. It turned out to be a pin hole in the top hose. Under pressure not a trace of a leak until it was pumped up to the rated 20psi/1.4 bar then a pin hole would open up.
In the case of this PT Cruiser it would seem air is getting rather than coolant out ---- but how ?
" We're trying to plug a hole in the universe, what are you doing ?. "
(Walter Bishop Fringe TV show)
So I finally did a Cylinder leak down test. And when you pressurized the Number 1 And 2 cylinders we would get bubbles back in the radiator. it was not a lot but it was obvious. So I have pulled the cylinder head. And will get it checked for cracks. And replace the head Gasket this week.
So this turned out to be a warped head. Cylinder leak down on 3 cylinders was about 40% and on the 4th it was about 50%. What is interesting is compression tests show only a 10 psi difference between the first 3 and the 4th.
.004 is the allowed tolerance. And we could get .009 part the straight edge in multiple places.
So now debating on a rebuilt head or having it milled. Or possibly a junkyard head I rebuild.
So purchased a rebuilt head. And put it on. But then it would not idle. Thanks to this channel and group I first started with codes. And yes it had the infamous to rich code. So naturally I start checking all sensors. Then it dawned on me. What really changed. The head and timing belt.
I was off by 2 teeth some how. So had to redo the timing belt. Just finished it today. So it is back on the road.
So much to learn really enjoyed working on this. It. Has been a long time since I have done this much on a car.
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