Re: [DML] Overheating, idle speed and stalling issues
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Re: [DML] Overheating, idle speed and stalling issues

A compression test will not definitively tell you what is going on. There are many modes of head gasket failure and it won't tell you if you have a liner seal leak. A leaky valve on a cylinder or worn rings can also look like a head gasket leak. A better test might be a differential leak-down test but the REAL test is going to testing for combustion gasses in the coolant. As Harold said, if you have a bad head gasket leak into the cooling system ,you would see other symptoms like blowing coolant out the pressure cap.
David Teitelbaum

--- In dmcnews@xxxxxxxxxxxxxxx, gmfm1@... wrote:
> I haven't seen anyone suggest a compression test on the cylinders to see if the head gasket is blown. Any reason you wouldn't do that to check the head gaskets?
> Thanks,
> Gary Masie
> ----- Original Message -----
> From: jedimasterglenn 
> Date: Sunday, April 15, 2012 9:22 pm
> Subject: [DML] Overheating, idle speed and stalling issues
> To: dmcnews@xxxxxxxxxxxxxxx
> > Need some advice (or a DeLorean mechanic to open shop in MA!!) 
> > on what to try next for what I think are 3 separate issues:
> > 
> > 1. I recently replaced my entire cooling system: radiator, 
> > fans & fan assembly, new water pump & thermostat, coolant 
> > bottle, and all the hoses except the ones to the heater core 
> > (all of them...even the small ones under the car). I added a 
> > valve (petcock) near the radiator to make bleeding easier. I 
> > have NOT put in any kind of self-bleeder system. I've bled the 
> > system several times per the instructions here 
> > (
> > delorean-baby.html). But every time I bleed it, I find air. I 
> > bleed it until there is no air. 
> > 
> > After bleeding, if I start it cold and leave it running/idling, 
> > it stays around 150F. When driving, temp stays consistent 
> > around 180F, but if I come to a stop for longer than a couple 
> > mins, the temp creeps up and will continue past 220. For 
> > example, I drove for an hour on back roads and highway today and 
> > it ran around 180F the entire drive). But when I got home and 
> > left it idling in the driveway, the temp started to rise as 
> > described. The new fans do work. I jumped them to test and 
> > also heard them come on at a bit less than 200F. I noticed they 
> > shut off when the temp went above 220...which I suspect is air 
> > causing an issue. And of course, I didn't let the temp go any 
> > higher and shut the car off. There are no coolant leaks that I 
> > can see and the coolant level holds at where I fill it (about 1 
> > inch over the main opening in one of the new stainless tanks). 
> > 
> > I have the fans wired to pull the air through the radiator from 
> > front of the car to back vs push...which I think is 
> > right...right? 
> > 
> > 2. Prior to the cooling system replacement and since, my idle 
> > speed has been rough. When I first start the car, the idle is 
> > good, hovering just below 1000rpms. But as it warms up, it 
> > starts to seek up and down between 800-1100rpms. I've checked 
> > the air flow meter inlet & intake manifold seals for leaks (I 
> > replaced all the manifold seals when I did the cooling system). 
> > I think these are fine. 
> > 
> > 3. And rounding out my collection of headaches is what I like 
> > to call the "downshift-stall mystery". I have a manual 
> > transmission. Again, this was happening prior to the cooling 
> > system overhaul. It doesn't happen consistently, but when it 
> > does it's always when stepping on the clutch and always at low 
> > speed, when downshifting(usually from 3rd to 2nd). I step on 
> > the clutch and the rpms abruptly drop to zero or close to it. 
> > Before I have time to shift gears, the car has stalled. 
> > Sometimes it shifts fine and other times it starts to stall but 
> > recovers. It idles without stalling, but as noted in #2, the 
> > idle seeks. Only thing I've tried is adjusting the idle speed 
> > microswitch, but to no avail. I have the microswitch set so 
> > that the throttle striker just barely trips the switch when the 
> > striker is at rest position. 
> > 
> > Thanks,
> > Glenn
> > 5391 
> > 
> >
> [Non-text portions of this message have been removed]


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