Hello, this is my first post on the Blazer forum and I was hoping to acquire some advice on my new purchase, a 1994 Oldsmobile Bravada (basically a Blazer) with a 4.3L Vortec which has 126K miles. I purchased it for a good deal, considering the body, paint, and interior are good, but it has a few issues which I need to address before I take it on a 1,000 mile trip next month.

First thing I noticed is that the coolant was low. I noticed this during the test drive, however the vehicle has no signs of moisture intrusion to the crank case or overheating. I recalled later that the 4.3 suffers from lower intake manifold gasket issues. I haven’t found a leak anywhere yet and since I topped it off, the coolant level hasn’t dropped in the 300 or so miles I’ve driven it. In your opinion(s), should I replace the lower intake manifold gaskets now, as this could potentially be the cause of the low coolant and it seems to be a common flaw with this engine?

Next issue that I didn’t feel on the test drive is an occasional miss at idle, a small stumble coming off idle, and some slight surging while accelerating. The worst episode was shortly after startup, I headed up a hill and couldn’t get over 35 mph or so, due to miss fires and a feeling of surging. I pulled over and let it idle for about 5 seconds, which basically cured it at that time. I haven’t been able to replicate it since. It runs totally smooth while cold and starts up quick every time. I haven’t replaced the fuel filter yet (will tomorrow), however I did test the fuel pressure and during pump prime, I saw 59 PSI of pressure, which dropped to around 52 or so after sitting for close to 15 minutes. While idling, I only saw around 53 psi, which I felt was low from what I’ve read so far. If the fuel filter doesn’t help, could it possibly need a new fuel pump or a new CPI unit? The car passed California emissions pretty well, which is fairly strict.

I will be performing a full tune up along with fluid changes as well, which the tune up may help a bit (in my experience, it’s rarely that easy). However, I figured I would ask for some advice from people who are familiar with these vehicles, in case these issues I’m experiencing are telltale signs of standard problems. I’d like to get it all sorted out sooner than later, so I’m not racing at the last minute before the trip. Any recommendations?

Thank your for any advice,
Dan

 

Welcome to the forum. As for the LIM gaskets, if you haven't seen any evidence of coolant in the oil and you have lost no more coolant then the gaskets could be OK, for now. Since it sounds like you intend to keep it your truck for a while I'd suggest making replacing the gaskets a priority preventative maintenance item. There upgraded Felpro gaskets to use.

As for your other issues, I'd try the easy stuff like check for vacuum leaks. A common issue is leaking by the under-hood vacuum lines that supply vacuum to the HVAC, and on Blazers, the 4wd system.

Be sure to search the forums on the recommended brand and part numbers of cap, rotor, plugs and wires to use (AC-Delco). You'll also learn the joy of swapping out the notorious spark-plug number 3!