Astro Van oil pressure problem

Ms Grumpy · #1 10-25-2014, 10:33 PM

I need your help with this one. Last night it was about 45 degrees, I was out and when I went to start my van after it had sat for about 3 hours I heard a noise that sounded a little like what a fan blade sounds like when it hits the shroud, or as David said it sounded like an exhaust leak to him. Anyway after about a minute the sound went away. I watched the gauges all the way home and nothing really seemed off. Now about a week ago I did notice that the oil pressure seemed to drop to about 25-30 when stopped, prior to last week it would usually drop just below 40 when stopped or at an idle and the highest it usually went was about 50-55. I checked the oil and it was within acceptable range.

Forward to this afternoon. Temp was near 60 and I started the van and the same noise from last night, this time it lasted for about a minute and a half. But when I went to pull out of the driveway I stepped on the gas and the oil pressure went up to 80, the highest on the gauge in the van. I was in the street and decided to turn around and park the van back in the driveway. The oil pressure stayed high until it shifted, then it would drop to about 50 and then rise again to 80 as I accelerated. I got back to the driveway and decided that I would see what would happen if I let the van get warm. As soon as it was warm I stepped on the gas and the oil pressure was back to normal. I pulled the van out and took it for a 15 mile city drive and it was normal. I parked the van and let it sit for about 1/2 hour and when I started it, the same BS with the oil pressure until I let it warm up.

I have talked to a few people and they suggested that I have the sending unit for the oil gauge checked. I am wondering if anyone has any suggestions for other things I should check or know of any issues like this with the Astro. This is a 2000 AWD Astro with 185,000 miles on it. We have taken pretty good care of this van for the past 10 yrs that we have owned it.

shadowgray396 · #2 10-25-2014, 11:00 PM

It could be an exhaust leak and as the engine warms up it will go away. My oil presuure goes up and down more that I have 125k on my pickup I have noticed. It could be a sending unit, but could also be your oil pump showing some wear on it. Putting a oil pressure guage on it and checking it that way would tell you if your sending unit is going bad. If the pump is worn the pressure at idle will go down.

chevymaher · #3 10-26-2014, 04:48 AM

I am On a astro forum. Oil gauges are notoriously inaccurate on these vans. Check the pressure with a mechanical one as shadow suggested. There is a 30 dollar oil sender in the back of the engine. I had to replace it on mine.

The motor mounts allow the engine to sag when they wear. Check the bottom of the shroud they have been know to hit there.

These vans have non-adjustable valves and they are set loose. There was a service memo called morning sickness. Where they valvetrain is noisy upon start up. It is a harmless thing. They make rocker studs which solve it.

It sounds like the oil just has some deposits in the engine starting to break up. In the oil pump there is a high pressure relief spring. It may be getting stuck. Sea Foam it and change the oil. Then all that junk breaks up and is washed out within the next normal changes.

Factory service manual says 8 LBS at idle is the acceptable low oil pressure limit for these 4.3's. Basically the red zone.

There is a counter balance shaft in them that rattles as well as they age as the gears that drive it wear.

There are several on the site that have over 300 thousand miles so they are tough. But this is a common issue. Just keep the oil changed and watch it a while.

That about it for the know issues I know about.

Ms Grumpy · #4 10-26-2014, 07:05 PM

Thank you guys for the information. Today I had to start the van and move it so I could cut the grass. The noise stayed on for the few minutes I let it run. But I did not have the same issue with the oil pressure going up high. If you are on Facebook I posted a video from when I first started the van and what it sounds like.

Ken Hayes · #5 10-26-2014, 07:54 PM

Change the oil and filter..........might as well get it greased too. It never hurts.

Ms Grumpy · #6 10-27-2014, 10:02 PM

After talking to a few mechanics and showing them videos of what it sounds like we are pretty sure we have a bad bearing or lifter. Either way it is time to make some hard decisions. Do we fix it, maybe a new crate motor, or do we look at buying something else. Not looking forward to a car payment if we go that route.

shadowgray396 · #7 10-27-2014, 10:17 PM

Lifter would be an easier then bearings. Usaully once one thing starts to go there are more to follow.

Ms Grumpy · #8 10-28-2014, 06:03 PM

Today we have been researching a few different possibilities. I consider myself lucky that I have another vehicle so that I do not have to rush into anything.

We have had the van for over 10 years and have become accustomed to having the room. We have been looking at newer vehicles for a while now and the cost of some of them is outrageous, and then to buy a vehicle a few years old is still up there. What to do, what to do.

I called a shop today that was recommended by my friend Tom. I was given a price of $2,500 for a used motor installed. Now that is cheaper than a rebuild on my motor, but it is a used motor with no warranty. I would rather pay more to get a rebuilt motor with at least some kind of warranty. I have some research to do on motors and on vehicles. If anyone has any ideas for me I would appreciate any help I can get at this point. Wish me luck.

chevymaher · #9 10-28-2014, 06:53 PM

Getting the engine in and out is the problem. I rebuilt my vans engine it cost around 600 bucks parts. Acid wash, cam bearings, rings, crank kit, gaskets. I did the work myself tho. I did other non-essential things while it was out. Ported it, valve job, springs and keepers. Big roller cam. Just being me.
It has been years and a incredible amount of miles later and it runs like a top. Mine broke a oil cooler line at 220 thousand. I got it shut off before it locked. I got 267 thou now.
If you like the van it well worth a rebuilt engine. They will last forever.

flash · #10 10-28-2014, 06:57 PM

I wish I had some helpful advice but I dont have anything ,new and used vehicle prices are absolutely crazy .Im considering buying an all wheel drive winter beater (Suburu) from a friend of mine in case of snowy weather hampers us again. It is not yet for sale ,it was his elderly mothers car before she passed away and has really low miles ,just got to wait til he is ready.