Hi there! I recently got a 1986 Fleetwood 75 Formal Limo for free. The car is clean over all, has a lot of potential. I have searched the forum (which is GREAT) and still have a lot of questions. *Yes, I'll be getting a GM shop manual but I am hoping to get the limo on the road sooner than later. Don't make me beg.


Coolant system over-pressurized when I flushed the coolant and changed the t-stat, car runs hot (I think, no idiot lights came on)...I am miffed as to why the car bubbles and shoots out air when I was trying to purge the air out. It NEVER stopped purging!!!

I am aware of the intake/head gasket problems on this motor, the oil is crystal clear and the coolant looks great when I drained both. The t-stat had some brown stuff on it, though. Car idles great when cold and makes decent power when I drove it on/off the trailer.

Hard to start when warm, stalls when shifting in gear, HIGH idle always. I think this is the coolant temperature sender, but I'll test it first. The Coolant/Fan warning idiot light stays illuminated when I have the key on, but none of the others do. Is that normal?

Power trunk pull down quit working. The glovebox release works, and both fuses are fine.

Where is the RELAY (not fuse) box on this car? The owners manual mentioned its hidden by a panel, but doesn't say where. I need to test the horn relay, as the horn is stuck on.

The stereo's AM/FM tuner and rear seat controls are possessed. Sometimes it works great, other times it will find a station, lock it, but never play it. If you go in the back seat and adjust things, sometimes you can get the tuner to play. It almost seems like a loose ground.

Power locks don't work, but I hear a relay clicking near the passenger side dash. (Is that where the relay box is?) And I hear the same clicking sound when I try to activate the rear door release button in the back seat.

The vacuum pump (under the battery) runs constantly, and most of the hoses were broken in half or crumbling. I replaced them. I pulled the fuse for now, but what does this thing do?



The car has 84,000 miles and it was supposed to be shipped overseas but the deal went cold. Hence why I got it for free. Here's the list of things I've changed to get the car running now:

The majority of vacuum lines
Ignition Module
Coil
Oil
Coolant
Thermostat
Brake fluid
One Caliper/Brake fluid flush
Power window regulator clip
Fuel Filter/Air filter
Serpentine belt
Alternator
Battery
Oh, and I installed a 1991 strut tower brace to triangulate everything. ;)

Get a Helm Factory Service Manual, like you said you will do.
This is the HT4100 engine which required the use of GM sealant tabs in the cooling system. GM part#3634621/AC Delco#10-108. Any AC Delco parts store will have them for a few bucks. The brown residue you noticed is that sealant that was flushed out when you drained the coolant. Not using the sealant was a main cause of engine failure on these V-8s.
The vacuum pump is there to maintain proper vacuum level for the cruise control valve/servo and other vacuum control systems.
#3=PD motor problem.....does the telltale illuminate when the key is Off? If so, the switch has a diode in it which is bad. The switch needs to be replaced. The motor itself may be ok (I just went through that situation)
#4...behind the glove box
Have you learned how to access trouble codes using the CCP? If not, look at the 'sticky' on this forum.

p.s. look on my profile for my email addu and send one.
great game last night!!

Get a Helm Factory Service Manual, like you said you will do.
This is the HT4100 engine which required the use of GM sealant tabs in the cooling system. GM part#3634621/AC Delco#10-108. Any AC Delco parts store will have them for a few bucks. The brown residue you noticed is that sealant that was flushed out when you drained the coolant. Not using the sealant was a main cause of engine failure on these V-8s.
The vacuum pump is there to maintain proper vacuum level for the cruise control valve/servo and other vacuum control systems.
#3=PD motor problem.....does the telltale illuminate when the key is Off? If so, the switch has a diode in it which is bad. The switch needs to be replaced. The motor itself may be ok (I just went through that situation)
#4...behind the glove box
Have you learned how to access trouble codes using the CCP? If not, look at the 'sticky' on this forum.

p.s. look on my profile for my email addu and send one.
great game last night!!

Great information, thank you! I replied to your PM but I don't have enough posts to send it. I bought that service manual, THANKS!

Follow up question for you:

#3: what should illuminate with the key off?

Nothing should illuminate. That is the warning of the diode problem. Have you checked the fuse under carpet 'at' the PD motor? That circuit is always Hot to the PD motor. One trick I came up with, that worked on my car, was to run a jumper wire from the release solonoid and touch the stricker at the PD motor. That would complete the ground circuit and let my motor run when I was testing/adjusting.
I know you can't send PMs, why I suggested you email me....click on my handle and it should display my addy.....I think...

This vacuum pump is probably, in fact, the air compressor for the rear level ride operation. Running alot means an air leak to the rear shocks. 86 Fleetwood 75? is this a front wheel or rear wheel drive car?

There is a vacuum pump on that year Deville but the Fleetwood is different line so dunno if it has one or not.

On the Deville it provides supplemental vacuum to help drive the brakes and accessories. The engine only puts out 15 hg inches and the vacuum pump boosts that up to 20-25 hg inches.