I have a 96' Blazer 4x4 with the 4.3L Vortec. When I started it yesterday morning the lifters started rattling, and the oil pressure showed 60psi -- a little higher than the normal 40psi. I turned it off, and checked the oil. It was about a quart low, so I drove my truck to a parts store and bought some Rislone Engine Treatment thinking maybe a lifter was sticking and this might free it up. I added the Rislone, and started it back up. This time I could tell that it was more than one lifter rattling. After leaving it running for about 10 minutes, the lifters stopped rattling, and the oil pressure dropped back down to its usual 40psi. I realize I may have caused some damage if there is no oil in the top of the engine, but I'm hoping that by using synthetic oil I've reduced those chances??

I drove it several more times yesterday and it ran fine and didn't do any rattling. This morning when I started it, the rattling was back, along with the 60psi oil pressure. I let it run for about 5 minutes this time before it quit. It ran fine on the way to work, and to lunch. When I started it to come home for the day... you guessed it. Again, I let it run for a few minutes and it quit.

I bought this Blazer new in 96. It has 109,000 miles on it, and up until this was still running like the day I bought it. I've been pretty good about maintenance, and I've always changed the oil every 5000 miles. I've been using Pennzoil SUV/Truck Synthetic Blend 10W-40 for about the last 15,000 miles. Prior to that, it always had Pennzoil 10W-40.

I've built a few small blocks in my day, but never had the pleasure of tearing down a 4.3 Vortec. I'm thinking there may be some sort of restriction somewhere that's causing the higher pressure, yet preventing oil from reaching the top of the motor. I'm not really sure how to tell where, or if this is even the problem. Any suggestions will be greatly appreciated!

Change your oil filter, it could be just a bad oil filter.

Where do you live? 10W40 is a little heavy weight oil for colder climates. That would explain the high pressure and slow flowing to the top end on cold starts. Also for me 60 psi is normal when cold then it drops to about 45-50 during driving after it gets warm.

I changed the oil and filter this morning. I used a NAPA Gold filter (made by Wix I think) and Castrol Syntec 10W-40. When I started it after changing the oil and filter, it did the same thing. Rattled for about 10 minutes, then quit. However, I have driven it several times today with a couple of hours between trips. The noise hasn’t come back yet, but the real test will be after it sits all night.

As for the climate, I live in central Arkansas. The temp here in the winter very rarely gets below 30. Most of the time it's 40-60. When this problem started, we had a cold front that brought us down to the 20's for a couple of days. When I changed the oil this morning, it was 68 outside.

I'm very aware of things like oil pressure and water temp. In fact, I've been accused at times of looking at the gauges more than I do the road... The oil pressure on this truck has been a little over 40psi at idle when cold since it was brand new. After it warms up, it drops to a little below 40 psi at idle, and runs about 50 psi at highway speeds. My concern about the oil pressure is because it's never been as high as it gets when the top-end is rattling -- a little over 60 psi at idle when cold. After a few minutes of driving, it drops to around 40 psi, and the top-end stops rattling at the same time. It's almost like there is a valve opening allowing oil to the top-end.

Before all of this, I have always used Fram oil filters without a problem. After reading many posts all over the net where people talk about Fram filters coming apart inside, and their anti-drain valves that fail almost instantly and bypass the filter completely in a lot of cases, I'll never use another one!

My concern now is that I may have a motor full of debris from a filter that came apart. I’m planning on cutting into the filter this evening to see if I can tell if it’s all still there or not. Maybe some plumbing in the block somewhere is stopped up??

Any other ideas???


Thanks!

I am having a similar issue in Colorado. When I first come out and start it up I hear a rattle like a lifter. I let it warm up and it goes away. then I noticed that I'm also hearing over 3400rpm. I haven't checked my oil pressure levels when it's doing the rattle vs. when it's not. Also is it possible this is a rod bearing going out?

I suppose it could be a rod bearing. I hope not! In my case, it really sounds like lifters. I've heard main bearings rattle under low/no oil pressure and this sounds totally different. It's more of a ticking that turns into a light knock at about 2000 rpm. But once it stops, it's completely gone at any rpm, and you can barely hear it running. I think rod bearings will knock when you rev a little and let off slowly.

It hasn't done it since right after I changed the oil and filter. I'm really hoping there was something stuck somewhere that worked its way out. I'll know in the morning…

I would change your oil filter first – especially if you’re using a Fram. There are a lot of people out there saying that Fram filters fall apart and clog your engine causing main/rod bearing failure, and all sorts of other fun stuff. Of course, I don’t know this to be fact. You can read some of them here à http://minimopar.knizefamily.net/oilfilters.html

10W40 I think is a little to much for these engines. It is probably why you were getting the ticking at the upper end. I myself go with 10W30 up here and have never had a problem.

10W40 I think is a little to much for these engines. It is probably why you were getting the ticking at the upper end. I myself go with 10W30 up here and have never had a problem.

The owners manual (you know the one that came in the glove compartment of truck) actually says not to use the 40 weight oils. They say to use 5w-30 if your temp drops below 0 or freezing (i dont remember which one) or 10w-30 for any other climate. The only difference between the 2 is that the 5w is easier to crank in the cold since its thinner. I run 5w-30 all year round up in jersey. running a winter weight oil in the summer will not hurt, if anything it will allow the oil to hit the top end faster getting rid of the initial lifter tick

I don't know if this is your problem, but it could be so I'll tell it just in case. My 2000 Blazer 4.3 (105,000 miles) had started getting a minor valve tap on cold starting about a year ago whenever the engine oil was about 3000 miles old. After an oil change, it would go away. It developed a bad valve tap about 7 weeks ago. I kept changing the oil hoping to flush out the lifters and noticed some very small non-metalic clumps of crud in the oil. They looked like little oval-shaped clumps of carbon, and I would have not even noticed them except that I drain my oil into a white plastic tray and they were at the bottom of the tray when I transfered the old oil back into the oil containers. After the oil change, the valve tap would go away for awhile. Then a couple of weeks ago, I started the car in the morning and the tap reappeared louder than ever (scary loud) and I noticed that my oil pressure briefly shot up to almost off-the-scale. The tap went away mostly after a few miles and I only drove it long enough to get the oil really hot. When I drained the oil, I noticed steam rising from the oil and knew it was a bad intake gasket. Sure enough, the coolant level was way down. As it turns out, I had a VERY small intake gasket leak for quite some time and it was enough to foul a few lifters. For the past couple of years, I had always had to add a little bit of coolant during oil changes, but never thought much about it. The old engine oil never looked coolant-fouled, there was no gunk under the oil filler cap, and the coolant reservoir always looked clean. This small coolant leak was enough however to put a steady small stream of crap in the oil which fouled up some lifters. Finally, when the intake gasket started leaking badly (must have been a few days before the bad valve tap appeared) I noticed it. To make a long story short, I replaced the intake gasket and all the lifters and the engine is running smooth and quiet now. I was afraid that I might have killed my main bearings, but I guess my very frequent oil changes and the very slow rate of coolant leak saved them.

Well, I think my lifter problem is solved. It was 30 this morning, and it started fine with absolutely no rattling at all. I guess there was something plugged that worked its way out, or at least I hope that's what happened.

I did cut the Fram filter that was on it open and found that it had basically disintegrated. All of the paper part of the element was falling apart, and the rubber anti-drain valve was in pretty sad shape. The thing that really ticks me off about it is that filter only had about 1800 miles on it.

It's a real shame that Fram continues to knowingly sell products that routinely fail. Someone should file a class-action, or something. Maybe one day when I have some free time I'll get that started. I’ve checked the domain name ‘framsucks.com’ and found that no one owns it. The .net, .org, .cc, and .tv versions are also available. I’m thinking that might be a few dollars well spent. I would even be willing to host the site on one of my web servers for free. If there is anyone out there that has a Fram story, please contact me at glenmoore670@hotmail.com (glenmoore670@hotmail.com). Who knows, maybe we can get them to pay for our time at least.

Thanks for everyone's help. It's good to know that there are guru's available with only a few clicks.

Thanks again!

Three things: #1 10W40 is too heavy, that's probably what's causing the noise. GM recommends 5w30 for several reasons, one of which is to supply sufficient oil to the valve train. #2 5,000 miles between oil changes is too long. Don't care what GM says on this one, no more than 3,000 miles. #3 If you have ever taken an engine apart that has used Pennzoil regularly, you know why you're taking it apart! Pennzoil and Fram, a technicians best friends.

#3 If you have ever taken an engine apart that has used Pennzoil regularly, you know why you're taking it apart! Pennzoil and Fram, a technicians best friends.

LOL, I agree on the pennzoil part.., frams no better either