Hello. I need to do a compression test on my mothers' 93 LeSabre and need information on how, exactly, to disable the ignition and fuel systems prior to testing. It'* been years since I last did a compression test and my experience is all from vehicles radically different from this one. I tried the 'search' function both here on-site and on Google - and wasted nearly all todays' daylight hours without finding answers. Seems simple, right? But obviously I've been going about it wrong somehow so I'm asking here: how do I disable the ignition and fuel systems on this vehicle so that I can safely test engine cylinder compression?
Many many thanks in advance to any and all who take the time to answer, it'd be much appreciated!

Disconnect the ignition module and the harness going to the injectors. There may be ab easier way if you have a vacuum gauge.
What is the engine doing? Is the engine light on?

Thanks for the quick reply carfixer007. For various reasons I suspect a possible blown head gasket.......coolant loss, overheat issues, some chocolate-looking foam on the radiator cap when I removed it........
I live in California, mom is in BFE (Fallon Nevada). Based on the things mom told me on the phone I bought a number of replacement parts online before heading up to (hopefully) get the car safely operational again. I did think to bring my compression test kit etc with my tools: I have experience in how things like this sometimes go and I hate to overlook the obvious or make assumptions based on insufficient or inaccurate facts! And I _loathe_ re-work ...so a bit of basic engine evaluation is time well-spent. My mother isn't always effective at communicating relevant details and I try to plan with that in mind but still frequently get caught out on some detail that I didn't foresee.
That said, I didn't bring my 'Mity-vac' and sorely regret that for more than one reason. (Went to move car, brake pedal sinking, no bueno!)
And finally, no dash/warning light. etc. OBD 1, had printout of blink codes years ago (not that I was ever certain that I was reading them correctly!) but gone now along with nearly useless Haynes manual.
Would you mind giving me more specifics on disconnecting the 'ignition module'? Such as what I'm looking for, the location/description? Details? Please? With those I _might_ be able to recognise it when I see it......... I can probably figure out the 'harness connection' for the fuel injectors myself....maybe.

Thank you. Disable the ignition system

The coil pack (with the 6 plug wires) sets on top of the ignition module. There are two connectors to the module. You can disconnect which ever one is easiest.
Sounds like head gaskets with the over heating and milkshake coolant.

So it doesn't matter which one I unplug? Either one will suffice?
And yes, head gasket(*) failure is what I fear....thus, why I want compression readings. But I don't want to cause 'severe engine damage' while attempting to evaluate its condition.

And again, thank you for your time and attention.

[edit by CathedralCub in bold] .....getting a clear answer from my mother to the overheating issue is nearly impossible. How bad? How often? What symptoms? When did it start? Moms reply (condensed version) : "it seemed to be getting hot. I can't drive very far, it gets hot. I had the neighbor (kid) remove the thermostat......."
Need I say that she didn't tell or consult me about this when it first became an issue....? Like pulling teeth sometimes......

[edit by CathedralCub in bold] ....I don't know how to edit my last post but it should have read "......getting a clear answer from my mother is ......"

Edit complete

I've seen more issues with intake manifold gaskets causing inter mix issues than head gaskets. On 95 and later upper intake manifolds would leak coolant from around the egr pipe, don't remember if 93 uses the same manifold. Just a couple of things to keep in mind so not to be "tunnel visioned".

Click the edit button, do your edits, then save before five minutes elapses from the time you posted the original post:

1996 got the Series 2 with that bad manifold design. Prior to that it was a different manifold.