Quattroporte III catch-all thread

Fantastic, thanks!

QP3 owners everywhere thank you

 

Seems issues are cropping up everywhere lately.

So a local (and competent) garage did some work on the rear wheel bearings, and checked and adjusted the timing. They didn't have time to adjust the carbs, and suggested I have a look at them with the Colortune. They said the timing was way off (retarded) by almost 40 degrees, and it was a wonder the car ran at all. Emissions sank from 1100HC to 10, CO2 fell to 0.9%, with lambda at 1.2 (i.e. lean). It also turns out that the rebuilt torque converter lacks timing marks. He found TDC and put a mark on it to work from.

The car started and ran ok after their adjustments, but without power. More alarming was that it overheated after 20-30 minutes relaxed driving. It's never done that, ever. At least as long as I've had it.

Today I used the ColourTune and dialed in the air/fuel ratio as best I could. On some cylinders it was very obvious, and the rpms increased noticeably as one approached the ideal mix/color, on others it didn't seem to do much of anything, but I found a color/rpm that seemed best and went with it. Almost all cylinders were lean compared to before. The sooty coating the plugs had from before was replaced in many cases with white or very light tan on the electrodes and insulator.

The engine pulls better and is more responsive now, but still overheats.

There don't seem to be any coolant leaks, the hoses appear ok and both are hot to the touch, as is the radiator itself. Due to the built up pressure, some coolant does end up on the ground from the overflow tank. I've added distilled water to top up for now.

If the thermostat was broken, I'd expect at least one of the main hoses and the rad itself to be cold, i.e. the water never makes it off the block and back to the radiator, but that's not the case. When I put on the heater, it worked fine and dropped the temperature a little bit, at least temporarily before it crept back up and the warning light came on.

If it was the water pump I'd expect some leak, or noise, or something. Both fans work and come on automatically. I don't see any white smoke coming out of the exhaust.

The thing that puzzles me is figuring out if this is completely unrelated to the timing work done, or if it's somehow (bizarrely) related. It's not something that happened gradually, the car very rarely gets over 70C, even on hot summer days and long drives. Idling for long periods could heat it up to 80C or so, but nothing like this. I was using the car regularly, everything worked, delivered it to the workshop, picked it up two days later and it overheats each and every time I drive it.

Any ideas? It's been a while since I changed the coolant, maybe I should start there, and flush the radiator. What coolant type is used for these alloy engines? Ethylene glycol, or O.A.T, or hybrid?

 

William, I hear that bantered about as well, regarding classic cars in general. But in almost 4 years of ownership it's never once overheated, even on long drives on the Autobahn at high speeds, or idling for long periods while we've tweaked the carbs. That's the one problem the car has never given me, and I wonder if it's something someone said once that has just been repeated over and over. It's not a 1950's or '60s car, by 1980 I'd say we'd entered the "modern" era where someone actually calculated the cooling requirements of the well known and proven engine and dimensioned the system accordingly. If it were a general problem, wouldn't I have had problems all along with the car since I got it? Logically speaking?

Mark - funny enough there is something weird going on with the vacuum that I need to examine closer. I noticed after I tuned the carbs yesterday when driving that the "consumption" gauge, which as far as I recall is connected to manifold vacuum, was always in the red, even at idle it was on the edge of yellow/red. I think green indicates high vacuum (e.g. the carb butterflies are closed) and as you press the throttle to open the butterflies, the vacuum drops, putting the needle higher into the red. Previously if I was very gentle on the accelerator I could keep the gauge in the yellow mostly, and in the green when cruising or keeping a steady speed. Yesterday is was in the red regardless of what I did, even on deceleration it just barely dipped into the green area.

I think you're right, I'll need to have them check the timing once more when I take it back in a week or so.

Mike, I haven't replaced it and have had the car for 3.5 years now. The other Mike (previous owner) did have the water pump rebuilt, I can't tell if anything's been done since. So that would make it anywhere from 2004-06 last it was done. On the other hand, it's a classic car that's driven lightly and only occasionally. But that might be something to look at as well.

Thanks for the suggestions. I'l have another look at the hoses and check the vacuum system while waiting for my next trip up to the mechanics.

 

My next hypothesis, related to the overheating. The "consumption gauge" used to be in the green at idle, yellow to red on gentle acceleration, red when giving a lot of gas. Which correlates with carb butterflies closed (high vacuum), partly open (middle vacuum) and open (low vacuum).

Now it's in the red all the time, even idling. Coasting downhill a few minutes ago, foot completely off the accelerator, the gauge was in the yellow. Barely.

I also notice that my brakes are a lot softer than before, almost mushy. Brakes use vacuum boost, do they not?

When I got the car back from the shop the idle was also set unusually low, like 500rpm or so.

The shop says they changed the timing by 40 degrees (advanced), and couldn't understand how the car even ran with the previous settings. But at least then it had vacuum.

My (new, rebuilt) torque converter also lacks timing marks. I wonder how they found TDC? Remove spark plug from no 1 cylinder and rotate the engine until the piston is at top?

40 degrees is a huge amount, is it not?

Would the changed timing affect vacuum? Could this be related to the overheating? The timing is off and the engine is unable to evacuate the combustion heat effectively because the cylinders aren't firing at the right point in time?

I managed about a 15-20 min drive today before the temp started creeping above 80C. Luckily I made it back home after a 45 min break to let things cool down, but it made it to 95C before I had parked. Just in the nick of time...

Wondering out loud. Feel free to join in...

 

I'll bet it's the starter solenoid.

I dropped one of these in and it hasn't failed to start a single time.

RobbMc Performance Products - Mopar Starter

(actually it has failed, twice. Once I forgot and left the car in Reverse, the other time it was in Drive. The Neutral Start Switch prevents the engine from turning over unless the transmission is in Park or Neutral. So both times were user error)

If I were you I'd also check the wiring from the relays & battery to the starter motor. Mine were shot.

 

Thanks Tony,

I saw that too. Finally heard back from the shop, who agrees it sounds like the timing still isn't right. I'm going to take a look at it in the next few days and see what I can do. It ran ok before but used lots of gas and had very high HC emissions. They've dialed the timing forward (advanced) by 40 degrees, it still runs (amazingly), and was lean until I dialed in the carbs last weekend, but still overheats and lacks power.

So probably the proper timing is somewhere in between the two. I'm going to verify TDC on cylinder 1 with a dowel or something and put a mark on the crankshaft pulley and work from there. It will save me the aggravation of having to be under the car and up in the engine room at the same time (I guess it was standard Italian policy to ensure as many jobs as possible - you can't set the timing alone on this car as it's designed!).

Is there any reason not to use the crankshaft pulley/"harmonic balancer" to set timing? I'll have to add a few marks with a marker, working with a protractor from TDC, but it should be the same as using the torque converter method, should it not? (my TC has no timing marks, inexplicably).

I'll see if I can borrow a friend's timing light, but will try using manifold vacuum initially and see if I can at least get it in the ball park (e.g. find the setting that gives the highest vacuum, then dial it back 2 degrees or so). At the previous settings I had good vacuum but poor combustion (high HC emissions), at the current ones I have poor vacuum but great emissions.

Thanks again for all the suggestions.

 

Had a look at the engine today.

First, there doesn't appear to be a bolt on the end of the crankshaft, but 5. I didn't try finding TDC by hand turning the engine, since it seemed non-trivial.

Working from the distributor position that the shop had set, I slowly turned it first one way, then the other. At both extremes I could hear the engine slow down and start missing. I found the point that appeared to give the smoothest idle and left it there for the time being. The shop said they had to move it 40*, which sounds crazy. I moved it probably a total of 30* or so end to end and landed somewhere in the middle. I can't imagine how the car even ran if it was 40* away from the current position....

First question - I looked in the manual, but couldn't find which direction is advance and which is retard on the dizzy. Looking at it from above in the engine bay, does turning it clockwise advance or retard the timing?

Measuring vacuum, I realized I know even less about engines than I thought (grin). The vacuum to the distributor advance is constant and steady at 25" Hg, regardless of throttle position. Shouldn't it decrease as one depresses the throttle?

The vacuum from the manifold read between 5-10" Hg and fluttered rapidly between the two. Accelerating dropped the vacuum to close to 0, releasing the pedal brought it up to 15" (still fluttering) before settling back at 5-10". Gradual acceleration increased vacuum also, a little.

I figure I must have measured wrong, I used the hose coming off the front of the manifold, both with a T to leave the rest operational, and just connected directly to the gauge. Since the cam covers have a breather hose that connects to the same vacuum system, and to the front bottom of the air cleaner box - open to the ambient air, wouldn't that mess up vacuum readings?

Anyway, the car has stopped overheating! I also have the "consumption" gauge needle back where it used to be, right on the transition between green/yellow at idle, into the red on acceleration, and back in the green on deceleration. The car also responds to the throttle better, but is still running very rough.

I had readjusted the idle mixture screws after getting the car back from the shop, and of course after moving the distributor to the new timing settings she was running way off. So I went back to my Colortune and found that all cylinders were running much too rich (that explained the continual backfiring every time I let up on the gas pedal), plugs which last time were white from a lean condition were now all sooty from running too rich. I leaned them all out, so now all are between 1-2 turns out from seated, most about 1.5 or so, give or take 1/4 turn. There were a few cylinders where combustion appeared intermittent, instead of constant. I'm not sure what would cause that.

What I notice now is that the car idles well, and the slightest touch of the accelerator translates into movement, I can feel the engine pulling much better now than before. She's still backfiring, but not as often, and in different places. The worst thing is that acceleration is "lumpy". From a standing start it's pretty good, but as soon as I get up to 2000rpm and more it's almost like it misses a beat or surges forward and backward as it accelerates. I'm not sure why, but wonder if maybe the distributor is proving a touch too much advance, and when the centrifugal advance sets in (which would be 1500-2000 rpms or so, up to 3-3500 rpm) it's over advanced. I didn't hear any signs of pinging, but the engine is so noisy to begin with I'm not sure I would be able to in any case. Thus my question about the rotational direction of the dizzy and advance/retard. I want to pull it back a few degrees and test it again.

I also managed (not sure how) to break the "microswitch" under carb no 1, the cable came off in my hand with the switches guts on the end. Oops. What exactly is the function of the microswitch, and is it present in all cars, or only US cars with emissions equipment?

Well, at least I learned some stuff today, and actually got the car to stop overheating.

Tips/suggestions/experiences/advice are all welcome!

 

I love the part in parenthesis: "not yet manufactured by Maserati" (referring to tool #7)

No idea, how can I tell?

Also, I must be reading vacuum incorrectly. It can't be fluttering between 5-10" Hg as "normal". Maybe I should disconnect the brake booster and measure there, instead of the pipe that goes directly to the front end of the intake manifold? Should I use a Tee, or can I just plug into a line and leave the rest unconnected? I've seen both, and am not sure how the vacuum system on the QP3 works (still).

Thanks for this. I might go back and turn it clockwise a few degrees and see if that cures the "lumpiness" on acceleration.

I think they did it to ensure more people would be employed. Italy had a red government at the time, very pro-labour. Timing underneath while you rotate the distributor on top means you have to have two guys, it's impossible to do it alone...

Tool #7 shouldn't be that difficult to make. In fact that would be something that would be perfect for the 3D printing going on, in stainless, as long as it is strong enough to take the torque involved turning the engine over.

A timing wheel, either temporary, or some sort of thin sticker that can be attached to the edge of one of the crankshaft pulleys along with a pointer or mark on the block would be awesome, and long overdue . Even something that just attaches temporarily to two of the bolts on the front pulley (they'd need to be marked somehow for reference) and won't fly off while setting the timing, then removed when set and stored for later would be great.

 

Sounds like your neutral start switch, or the shift lever setting (when it's in P, it isn't completely in P). It won't start unless in P or N because of the neutral start switch on the transmission. It breaks the starter circuit if the gear lever isn't in P or N.

Just a suggestion as to where to look.

 

Mine is identical to yours, methinks. 1980 model with the service manual vacuum system, including the EU air cleaner cover (not the "cakebox").

My thoughts exactly. How often do you really need to do this? Set and forget, at most once a year during an annual checkup.

Cool, will have a look and see what I can find to dye the parts.
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