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!

 

What type of oil filter are you running? I believe that the filters incorporate an anti-drain back valve and I suspect that this is the source of your problem. If the oil is allowed to drain back down into the pan, it will take a little while to get back up to the top of the motor, especially in cold climates.

 

I'm using a Fram PH3980. The temperature here has been in the 20's at night, and that's when it started doing this. I wondered if it was temp related, but I figured the oil warmed up fairly quickly, and didn't think it could take 10 minutes.

The filter isn't mounted on the block, it's mounted on the frame (I think) just behind the bottom of the radiator. When I went to check the filter, I noticed that there is a little oil dripping off of the hoses going to the block the oil filter mounts to. Do you think this might be related?

 

I was afraid you were going to say Fram. Fram filters has one of the weakest anti-drain back valve designs. I would first try either a Napa Gold, Wix, Purolator, Pure One, or AC Delco filter. All of which can be purchased for around $5 and under. They are pretty much the best of the best for the price. I run either Pure One or AC Delco filters on my vehicles and it all depends on what store I go into to buy them.

I had a very similar problem to this on my '94 Intrepid and it was because I was using Fram filters. After an oil change and new filter, it would quiet down for a bit, but then come right back again acouple hundred miles later. Put on a quality filter and the noise went away for good.

Atleast if you try this, you can rule it out. It should only cost you around $5 for the filter and another couple bucks for the oil to top it off again (unless you are close to an oil change anyway).

Give that a try and let us know how it went.

 

*clickity* Engine oil filter study link. May help you decide the next oil filter you install.

Here is a link on filters. It's written by a cyclist no doubt but indeed interesting.

 

Well, I took your advice and changed the oil and filter. I used a NAPA Gold filter (made by Wix they said), and Castrol Syntec 10W-40. When I started it, it did the same thing. Rattled for about 10 minutes, then quit. The oil pressure was still around 60 psi while rattling, and dropped to just over 40 psi after the rattling stopped -- a little higher than it settled down to before. I'm guessing that's due to the fresh oil???

I've done quite a bit of reading on oil filters since reading your first reply. There are countless people out there that have had Fram filters come apart inside, and flood their engines with parts of the filter, and dirty oil. It seems that their "anti-drain" valve is simply a joke, and routinely fails shortly after installing a new filter in a lot of cases. When this happens, the oil basically by-passes the filter element, and isn't filtered at all.

I've ALWAYS used Fram filters in all my autos, bikes, and even my Deere tractor. I've done this because I remember my Grandfather telling me that Fram was the best out there. He was a Mechanical Engineer for Ford from the middle 1940's until he retired in 1975, so I took his word as the gospel. Of course, he gave me that information in the early 80's, and that may have been the case back then. Who knows...

The problem I have now is trying to decide what to do next. I suppose there is the possibility that something is plugged, and may work itself out. Then again, I feel like every time it starts rattling it's a good indication that there's no oil in the top half of the motor. For obvious reasons, this is a very bad thing. I don't want to give up on it though, and I really don't want to take it somewhere to have them tell me that something is plugged and the only way to fix it is a teardown or new engine.

Is there a way to flush it somehow? What would happen if I pumped some solvent (or something) through the lines that attach to the oil filter block? I think the close tolerances would prevent this, but I'm not sure. Also, where does the oil sending unit take its reading? Is there another place I could check oil pressure using a manual gauge to get an accurate reading of top-half pressure at start up?

Thanks for all the advice -- I really appreciate it!

 

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. 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!