97 SL2 Reconditioning

[Cheyne]

Hi All,

Due to the kids getting bigger, I picked up a low mileage 1997 SL2 with ~38K today. I probably paid too much for it but decided to go this route and hopefully pass it along to the kids in a few years.

Despite the mileage, I realize that there are some things that will need to be addressed due to the age of the car and the appearance that much of it is original and no service records in my possession. So I wanted to do a thread and ask what things I should probably address that would be more age related than mileage related.

With that in mind, the first two things will be the oil and cooling system. I noticed some varnish on the oil dipstick but could not note any burning yet on a 650 mile trip. I plan on changing it over to synthetic immediately and hopefully clean up what is already in the engine. I do have some of the good top end engine cleaner that I picked up on Ebay around a year ago but may wait on that until I get a grip on any oil usage.

The car runs stone cold at 1/4 or a half needle-width below. The ECTS and thermostat are first on the list on the cooling system. I would assume the two radiator hoses should probably be replaced due to age unless I can determine they are not original. What about the radiator? I guess that it may be ok unlike hoses that could dry rot. I'm also going to take the opportunity to flush out the Dex-cool. I don't like it, as I've seen what it does to the gaskets in a 350. Not to start a debate, mind you.

I also noticed a floor buzz that I'll check to see if is mount related a little later. I noticed when I finished the trip that the transmission was in performance mode and don't know if that may have something to do with it. I can address that after the oil and cooling system. I do plan on changing it over to synthetic trans fluid, although there's a white filter on it indicating that it was serviced at some point.

It's a pretty good little car, drives tight and straight with a good body. Some minor corrosion from the salt air but overall very good. Just needs a little TLC to bring it back up to spec. There are several things to do while assuming a 30K service interval but wanted to start with this.

Thanks.

[jimboman]

Sounds like you have a good program for restoring this SL2.

The radiator, if it is original, is probably near the end of its service life. These radiators are expected to last ~10 years from what others have told me. You can check for cracks in its plastic to see if it's near the end of its life. Maybe you can just have a replacement radiator priced and ready. That's what I'm planning with my SW2, since the original radiator is still good.

[Cheyne]

Oh well, I should have checked the readiness status on the monitors before having it tested today. 3 not ready: catalyst, O2 and EGR system. Sounds like it's not reaching open loop and will need to get it heated up and make sure no DTC's pop up.

Confirmed that the hoses are original.

[fdryer]

Open and closed loop occur in that order - cold engine start up always runs in open loop as the O2 sensor takes the longest time to heat up (>600F) before it outputs valid signals for the pcm to use it. With all sensors operating as the engine warms up, the EFI system stays in open loop mode until sensing O2 signals where it switches to closed loop mode of emissions control.

Some things that are mileage/age related; oil and filter, battery/alternator check on voltages (battery output>12v, alternator output >13.3v), worn/loose drive belt/tensioner, spark plugs, plug wires, cleaning ignition system and throttle body.

If mileage is genuine, below 50k miles, the radiator may be in great condition. Hoses bulging in diameter larger than their clamps indicates replacement is needed. A general rule of thumb with anti-freeze is to flush a system before using any anti-freeze of choice so mixing is avoided. No chemical reaction occurs if mixing coolant but the better coolant loses its long term capability against the coolant with a lower life rating (otherwise mixing won't hurt anything).

Replacing the coolant sensor and t-stat should correct any low temperature operating issues that may interfere with the on-board emissions self tests - going from cold engine/open loop requires engine coolant to warm up beyond 140F/160F as part of the readiness monitors (parameters). Once all the parameters are met, while the engine warms up (some require 'the drive cycle' as speed is one of the parameters used to monitor temperatures, map sensor, throttle position, the sealed fuel tank system using the evap canister, fuel vapor pressure and vacuum, etc) the EFI system leaves open loop and enters closed loop mode. Closed loop mode begins in about 2-3 minutes, maybe less as the O2 sensor is the last to send signals to the pcm. During closed loop mode, emissions self tests are completed. At anytime when a sensor isn't operating correctly, emissions testing halts - the readiness monitors won't go 'ready'. The items shown on readers 'not ready' indicate where testing halted. Readers won't point out what caused the testing to stop. All emissions tests are done in sequence and a list of parameters and which sensors are seen by the pcm is not easily found. Reverse troubleshooting determines which sensors come first and can help determine why readiness monitors halted from the monitors displayed. Emissions self tests are done every time OBD II engines are started/car driven/engine shut down.

[Cheyne]

Must have had it backwards on the open and closed loop. I replaced the ECTS (cracked), cleaned the connector (slight start of corrosion), replaced thermostat, hoses (not too bad), cleaned the reservoir and flushed the system thoroughly. Now running a full 7/16.

Changed it over to Mobil 1 extended performance with a M1-209 filter.

I'll drive it Monday to see if I can get the readiness monitors to set and then on to the transmission fluid. I'll need to order some filters with ignition parts and belt from Rock Auto. It still has the Packard wires on it, so I'm assuming everything is original except for the transmission fluid and battery (Interstate in it that appears new). Transmission fluid is fresh but I don't know that they didn't use Dexron VI.

One thing that surprises me on this is the rust that I found underneath on a FL car. The subframe has rust on the driver's side like something leaked on it. I'll get some rust treatment from work. That and a wire brush should do some good. It's nothing like a car that has seen salt covered roads but still nothing like we normally see in GA with no rust.

Floor buzz is still there.

[Cheyne]

I drove it a little and now the monitors all show complete with the emissions screen showing as "pass". That's good, but ... there were 2 codes in it: P1620 & P1624. I do not know if these were already present, as they won't cause an SES light. I guess the low coolant circuit may be from where I flushed, refilled and bled the system? I'm not sure if the other is related to that or the ECTS. No signs of leaks thus far.

I'll hopefully get it to the shop for the test in the next few days.

Floor buzz may be from the mounts. Original top, solid mount looks dry-rotted. I imagine that the torque struts are not much better.

[Cheyne]

The temp gauge also jumped quickly to 1/4 and acted slightly erratic for a little while before it appeared to settle down some. Hopefully it was just the system bleeding itself. If not, I may have to change the ECTS connector.

[fdryer]

With the readiness monitors now showing 'Pass' and no more SES indicator, you're car already passed state/federal emissions. You can ignore the remaining error codes as they're stored in history and not used for state emissions testing. As long as the SES light is off and readiness monitors 'pass', your car is 100% in compliance. The history codes are stored for 40 consecutive engine start/shutdown cycles for more advanced troubleshooting if these error codes remain and the SES light stays ON. After 40 cycles of error-free codes these codes disappear.

DTC P1620 Low Coolant Circuit
DTC P1624 Customer Snapshot Requested - Data Available

[Cheyne]

Yes, sir, it will pass. After I have it tested, I may clear the historical codes just to monitor it from there.

Thanks.

[almoore]

The battery is on the drivers side.I think some acid makes it down to the subframe.They always rust on that side.

[Cheyne]

Battery acid or coolant would be my guess. Battery tray shows signs of corrosion.

[Cheyne]

It passed emissions. I have received most of the parts that I've ordered and will get to work here soon on a laundry list of preventative maintenance.

Originally Posted by fdryer

Some things that are mileage/age related; oil and filter, battery/alternator check on voltages (battery output>12v, alternator output >13.3v), worn/loose drive belt/tensioner, spark plugs, plug wires, cleaning ignition system and throttle body.

I had planned on all of this with a number of other items except the tensioner. Question is: I hadn't thought of the belt tensioner as age related but definitely could see how it could be having been tensioned since 97. Is this something I should do while replacing the belt and mounts on passenger's side or leave it be if there is little deflection and voltage is good at battery? There is no noise in the belt drive. I did find the OEM tensioner for ~ $88..

[fdryer]

If you see the belt flopping with the engine idling, the belt tensioner may be worn. If you can deflect the belt between pulleys with just your fingers then the tensioner may be worn out. Squealing in the morning start up is another sign of a worn out tensioner. The alternator outputting >13.3vdc is a good indicator of the belt and tensioner working. Use good judgment.

[Cheyne]

It was a rather productive day installing the parts that I have received to date.

I could not deflect the belt by hand. Battery voltage at rest is 12.62 and at idle is 14.6. The tensioner and charging system appear to be fine.

Thanks.

[Cheyne]

I was a little surprised at the carbon on the top of the pistons when I changed the spark plugs. There was also oil on the threads of the #1 plug when I pulled it, so I changed the cam cover gasket yesterday. The top end doesn't look bad and the Mobil 1 EP should clean it up more. The cover cleaned up fairly well with a little degreaser.

I will probably soak the pistons with the old GM top end cleaner when I get to the next OCI which will may be shortened since it is the first that I have performed. It may help since the top end isn't bad and the cover cleaned up fairly easily.

[fdryer]

Carbon deposits are expected since combustion creates byproducts. Mix in more oil consumption than normal and this creates more deposits. Hopefully, GM's top engine cleaner will loosen any hardened deposits on the oil rings to prolong engine life by consuming less.

[Cheyne]

Hopefully so. I had just hoped the tops of the pistons would have been a little cleaner. I have yet to determine any oil consumption. It did not appear to burn any during a ~650 mile road trip, but time will tell. The plan is to run the Mobil 1 EP for a little while to clean it up and then soak the pistons before the next oil change.

[Cheyne]

Ok, so today was not as productive. I figured I'd take care of some other things before working on the car and ended up nearly dropping this on me.

It gives a whole new meaning to taking the shirt off of your back. I actually felt worse for my dad as it scared him more (yellow shirt). The shirt goes in the saw case as a reminder to always be careful when doing a job no matter how often you've done it before. And also, don't forget to COMPLETELY remove the forward wedge. This for a guy that uses extra jackstands and the jack when working around cars.

Just plain stupid ...

Hopefully no well-deserved flames, as I've already done that to myself all afternoon.