1989 D100 3.9 clean up

[urrlord]

I recently picked up an 89 D100 3.9 shortbed w/auto.The truck seems to run good but for 2 things, a high idle for about 15 seconds after it is cranked and the oil light flickers occasionally at low idle while in gear but the oil gauge needle stays in the 40-50% area of the scale.The truck apparently has around 120k on it,but the history of it is a bit murky. It had been purchased from a police seizure auction.The truck sat up a few(2-3) years before it was auctioned off.The purchaser replaced most of the braking system did a tune up and used it as a work truck for a year.He hit hard times and was forced to sell it.The interior is pretty good other than a 3 inch tear in the driver side seat cushion.The exterior has a dent above the driver side tail light and a small scrape on the passenger side of the bed.It definitely needs paint but there is only surface rust .

The engine has a bad valve cover leak,does not smoke but seems to burn a little rich.This is my first 3.9 EFI V6..I always had slant 6's and 318's in my Dodges.I'm thinking I may need to run a clean up oil change as the oil in it is very dark but still somewhat transparent.I may add some MMO or other cleaner for a bit and change the filter.

As a side note the filter on this engine is small,cross ref's with my Trackers 4 cylinder.Is there a larger filter that will interchange?Any suggestions would be appreciated.

So I have a v.c. gasket replacement and oil sending unit replacement(which seems more likely than an oil pump failure on these engines from my research) and a possible engine flush in my future.

For the follow up o/c I have Ace Hardware conventional 10w30 and 10w40,10w30 Maxlife semi synth,Pure lube semisynth 10w30 and 5w30,Kendall titanium 10w30,Smitty semi synth 10w30 and 10w40.Any suggestions?I'm leaning toward the Ace oil for 3-5k with a filter change midway and then move to the better oils.

The tranny shifts fine,fluid looks good.Brakes and steering are good,I may do a fluid exchange on them anyway.I plan on replacing all of the rubber line etc under the hood.Any other ideas?

Any personal anecdotes with this engine or type vehicle?
Thanks people.

 

[Garak]

Your idea about the Ace oil for a quick OCI sounds reasonable. After that, I'd be wanting to try some MaxLife.

 

[95busa]

I had a 90 dodge 318 auto. I did valve cover gaskets and serviced the trans diff and a few other things. ECU went bad so I sold it. Good trucks....mine called for ph43....mid sized between ph8a and ph16. I ran 15w 40 in it.

 

[fdcg27]

You could change the valve cover gaskets first.
This would give you a look inside and you'd see just how clean or dirty this engine looks internally.
You could then plan a clean-up program based upon what you find.

 

[Charlie1935]

Originally Posted By: 95busa
I had a 90 dodge 318 auto. I did valve cover gaskets and serviced the trans diff and a few other things. ECU went bad so I sold it. Good trucks....mine called for ph43....mid sized between ph8a and ph16. I ran 15w 40 in it.


My 87 with the 318 had the small filter (ph43) when new.
At the first oil change I went to the larger size (equivalent of PH 8A) ever since. Still doing good at 175,000 miles.

 

[eljefino]

I had a dakota 3.9 and there was some slightly convincing reason to use the short filter (PF16). I forget what it was, now, of course.

It's also possible the 4x4s would have the filter hit something, and they didn't want the lube techs screwing this up.

Mine was a 92 and had the Magnum heads... read up on them on allpar.com, they made more power. Iacocca made them turn the 360 into the V6 by lopping off two cylinders when they came out with the dakota as there was no way the slant 6 would fit. By this point they had the motor and figured they'd stick it in full size trucks also.

I ran 5w20 b/c I got some cheap (bad excuse) and had the oil light flash at hot idle. Eek! For your truck I'd run 15w40 or whatever 10w40 you have laying around.

 

[urrlord]

Originally Posted By: fdcg27
You could change the valve cover gaskets first.
This would give you a look inside and you'd see just how clean or dirty this engine looks internally.
You could then plan a clean-up program based upon what you find.



That was part of my plan.I did not make that clear in my OP.Sorry.That way I can physically clean up any crud under there.Good advice though.Great minds think alike (though my wife may disagree).

Also ,as several have suggested a heavier weight oil may be in line.Start out with the 10-30 for the initial cleanup and see how that goes.I get the feeling that 10-40 or 15-40 may be in its future.

 

[Red91]

If the oil light flickers you might try dropping the oil pan to check the oil pump pick up screen. If it's dirty, you might remove it and clean it. After that I'd start your clean up routine.

 

[fdcg27]

There may not be all that much crud under there.
If the engine saw anything close to reasonable OCIs, it may not be all that dirty.
I'm with you on replacing the oil pressure sender as a first resort, since it is the most likely culprit and it will be a much easier job than to R&R the oil pan, which could end up as your second resort.
I would probably run a short first oil change or two using something cheap.
Let us know how this all goes.
Incidentally, it sounds as though your wife and mine might have much to agree on, at least out of your or my earshot.

 

[tiger862]

Go get the oil sender from Dodge. Replace some with aftermarket only for light to come back while in gear. After dealer part no more light. The oil pressure at idle is really low and that is the reason for dealer item. Mom's Chrysler V6 had same problem and was told by independent shop she needed an engine and she has since put additional 50k on it. 150k and still going strong.

 

[artificialist]

Originally Posted By: tiger862
Go get the oil sender from Dodge. Replace some with aftermarket only for light to come back while in gear. After dealer part no more light. The oil pressure at idle is really low and that is the reason for dealer item. Mom's Chrysler V6 had same problem and was told by independent shop she needed an engine and she has since put additional 50k on it. 150k and still going strong.

I am not surprised. I have lost count of how many cheap aftermarket sensors I have replaced, because they aren't as accurate as OEM sensors.

I would have recommended the same thing, had you not posted this first.

Anyway, how do you know your engine is so dirty inside that it needs major clean-up? Is the heavy buildup on the dipstick? The idea of replacing the valve cover gaskets and seeing how much sludge is present is also a great idea proposed in previous posts.

Be sure to replace your PCV valve, preferably with the OEM part. Those can sludge up in even the most well maintained engine, and the spring will always fatigue over time. Some MOPAR engines from that time used a CCV system, which had no replacement parts and worked fine so long as the passages never sludged up.

Since this van is in unknown condition, I would get ready for stripped threads on a drain plug or oil pan. It is common on any vehicle with a steel pan and numerous services at quick lubes.

Often you can replace the filter with a MOPAR M-090 or equivalant, but I am not sure about your specific model. Other times a Motorcraft FL400 or equivalent may work.

You might want to replace the gear oil in the rear differential, almost nobody does.

See if your ATF is clean too. The smell test doesn't work on Chrysler ATF+4, that stuff stinks when brand new.

 

[urrlord]

Artificialist--Whenever I buy a used vehicle I usually do a cleaning and a fresh o/c,freshen up the power steering and brake fluids and check the rear end .Also the truck was seized in a drug raid and most druggies don't take great care of their vehicles(their money goes for other things).Then it sat up for 2-3 years so I'm being a bit more comprehensive about freshening up the truck than usual.Although come to think of it the VC leak is pretty bad and would have forced a continual adding of oil for the past year.So it may be pretty clean by now between the leaking of dirty oil and fresh detergent oils.Ha! I may be lucky.In addition the truck looks pretty rough,but runs good so that always makes you want to do more to it.

tiger862--Good call.I had not considered that.I was just going to get an aftermarket unit.

The atf is medium red and does not stink,the tranny shifts fine.So hopefully no worries there.

I drove the truck 220 miles after purchase with no problems.It got 20+ mpg on the drive at speeds up to 75mph.

The only problems were the driver side wiper shaft is stripped and needs replacing .That made the drive home in misty conditions that caused a build up of salt grime on the windshield somewhat nerve tightening.Luckily I had some glass treatment in the car my wife was driving.We pulled over and put a good cleaning on the windshields of both vehicles.
And the truck needed tires really badly.

But I'll get all that sorted out in the next few weeks.

 

[95busa]

Originally Posted By: eljefino
I had a dakota 3.9 and there was some slightly convincing reason to use the short filter (PF16). I forget what it was, now, of course.

It's also possible the 4x4s would have the filter hit something, and they didn't want the lube techs screwing this up.

Mine was a 92 and had the Magnum heads... read up on them on allpar.com, they made more power. Iacocca made them turn the 360 into the V6 by lopping off two cylinders when they came out with the dakota as there was no way the slant 6 would fit. By this point they had the motor and figured they'd stick it in full size trucks also.



The 3.9 was a cutoff 318 not a 360. In addition to aluminum heads, Chevy style rockers, multiport injection, high flow exhaust manifolds, and a hotter cam were on magnum 3.9 and 5.2 starting in 1992. The 360 got the magnum treatment in 1993.


















I ran 5w20 b/c I got some cheap (bad excuse) and had the oil light flash at hot idle. Eek! For your truck I'd run 15w40 or whatever 10w40 you have laying around.

 

[95busa]

Whoops....hotter cam. The magnum 3.9 and 5.2 came out in 1992. The 360 got magnum treatment in 1993.

 

[artificialist]

Originally Posted By: urrlord
Although come to think of it the VC leak is pretty bad and would have forced a continual adding of oil for the past year.So it may be pretty clean by now between the leaking of dirty oil and fresh detergent oils.Ha! I may be lucky.In addition the truck looks pretty rough,but runs good so that always makes you want to do more to it.

Maybe...
If you sense that the previous owner didn't maintain the van properly, they may have topped off their oil with cheap junk found at certain gas stations. That can easily lead to sludge. Even worse, they may have only added oil when they could hear the engine making bad noises.