DaveT

Coolant temperature sensor could cause that. 2 wire sensor under thermostat .

Iirc, there is more to getting to read memory mode than just connecting those. If you are getting a code without them connected, fix that fist. It will clear, then, if anything else is wrong, it will be shown.

I am not sure about what may be different on a DL. For my 87 GL wagon, and my 93 Loyale, I recently installed Rockford Fosgate P152 5-1/4" speakers. I used the existing black plastic mounting rings from the oem speakers, but cut off a rib that was made to fit a groove on the oem speakers. Drilled new holes in the plastic to mount the speakers, as the holes are different spacing. But then the mounting rings just bolted back in place. I also added weatherstripping to seal the speaker to the back of the stock door panel.

The biggest risk of running with a compromised cooling system - if enough coolant is lost that the temp goes above normal, it's headgasket time.

I don't know if it would be safe with your engine, I only know ea82s this will work - I put a short piece of solid wire around the valve on the radiator pressure cap, so that it makes a zero pressure system. Any leak will be far slower with 0psi vs 13psi. The risk is the lower boiling point at zero psi. If you do this, it is wise to check coolant level and air before every drive.

The oil passage seals in the headgaskets are copper, built in. The aftermarket gasket sets usually give you 2 plain thin (metric) o rings for the cam tower seals.

They should just slip in. No serious pressure or hammering needed. Sand the rust out of the pocket, and of that is clean, sand any paint off the new joint. I would not use the one that was hammered on. Apply anti seize to the pocket and the ball joint and the pinch bolt. Be a little lighter on the tightness, since the lube will alter the torque vs tension.

Search threads about head gaskets and intake manifolds. EA82 engine. There is a LOT of information about what to do, what not to do. It is not normal for coolant to be in those holes. Don't let the coolant get low - check before every drive, until you find and fix the leak. Running low on coolant to the point that gets an above normal temperature reading damages the head gaskets. The most common head gasket failure is combustion chamber to coolant. Intake gaskets can fail, letting coolant into the intake. This can be slow enough to not notice, unless you are checking the coolant level frequently. If you wait until an overheat, you now need head gaskets also. Been there, done that.

Wouldn't that big of a power increase require swapping the rest of the driveline to avoid breaking it? Also, the ej25s are known for headgasket problems.

Never seen anything like those pictures!

I noticed a few that were stuck in one head - the wire spring clip seemed to have worn / deformed the edge of the sleeve a little, rolling it into the groove on the lifter.

Yeah, too far for me.

Looks like burned out catalytic core. Normal working core is not black. I once had the core dislodge in one of mine. It moved around and mostly blocked the exhaust in the cat. The car ran pathetically. Weak. Didn't want to accelerate. Got it home. Did a few tests, and discovered the cause mentioned above. Could have just failed due to age. Or running rich, burning lots of oil, O2 sensor out of whack - but not so out as to trigger a trouble code.

The combustion pressure is very high. Way more than a compression test reading. I doubt the difference between 0 and 15psi in the water jacket is a significant difference. I think the main benefit is that more water is drawn back in during the cool down - the pressurized air would just cool and depressurize, and not draw any coolant back in. The zero pressure trick is really good at limping home if you have a coolant leak - like water pump seal fails, or hose or radiator gets a pinhole, etc. Even a cracked head - until the crack grew - but I got enough time to rebuild a spare engine.

There should be a wire that goes hot only when ac is on. A factory service manual with full schematics would probably help. When I got my 86 gl wagon ( same as loyale) The ac compressor was shot. I discovered that the ac compressor was always engaged. Found that someone had rigged a wire to force it always on. Don't know why. After un modified, the ac switched like it is supposed to.

I have done this with ea82 engines - take a small piece of 14 or 12 gauge wire, make a little u shape. Lift the check valve on the rdiator cap, and put it in there to hold it open. Bend it so it won't fall off. This makes zero pressure, and still allows for coolant to be drawn back in on cooldown. I have had no problems with boil over due to the lower pressure. Different engine may be different. Check coolant in top hose and overflow tank before every drive. Gotten away with this for months, but eventually the headgasket leak starts to get worse to where you can't use the car without risking overheat.

These are obd1 cars. That might be why the reader didn't work, guessing it's a new one. No cold start injector. Different map, yes.

The random idle stuff sounds like the Coolant Temperature Sensor. 2 wire sensor under the thermostat. The trouble code may or may not indicate that. That sensor can fail in a way that causes your symptoms without throwing a code.

The trouble codes are blinked on an LED in the ECU. Under the steering column. Remove the plastic panel to see the hole in the ecu where the led is. If the CEL light is on, it will be flashing the current code. You don't need to connect the test connectors.

Turbo vs non . Lots of different. ECU for sure. I can only guess, but likely sensors and wiring and instrument cluster.

Timing belts usually fail before 60,000 miles in my experience. The ball bearings in the idler and 2 tensioners are pretty near end of life around 50 to 60 k also. Even if they were still ok, they won't be by 100,000.

The big problem with waiting until a hose fails, is that you are gambling that you will immediately know you lost coolant before the engine begins to run above normal temperature. This window is very small. Over normal temp due to low coolant = new headgaskets. Sooner or later, usually closer to sooner.

Sounds like alternator dieing. It might be intermittent. My experience with more than a few is that original ea82 alternators get to around 150,000 miles and one of the brushes wears out. Other things also, but that one is like clockwork. Would not hurt to check the connections from the main out to the fusible link box and battery also.

I'd replace the bearing. It's going to fail soon. I don't know the specifics of that model / year, but usually those idlers use a standard ball bearing. Numbers usually printed on the side seals of the bearing. Get one with contact seals.

The factory specified thermostat opens at about 190 degrees. That's going to feel pretty toasty.