I have a 2001 blazer lt 4x4. The other night I started it and heard a loud knocking/ticking sound coming from engine. At first I thought it was a rod, but after about 5 minutes of running, the noise went away. I turned it off and started it up and no noise. The next morning, same thing. Seems to only make the noise when cold. Now it only makes the noise for a second or two during a cold start up then goes away and sounds fine. I've been thinking that it can't be a rod knock, but possibly a noisy lifter. I have also a cel for a fuel pressure sensor and I also noticed that it is possibly loosing a little bit of coolant but cannot find the leak. Also, the oil dipstick has a smell of gasoline. I don't know if a fuel pressure regulator is bad and I have a noisy lifter. I have no idea. Truck has 168k miles

 

I see what your saying ! it could be the intake gasket leaking or the fuel regulator leaking gas into the oil ! I would change the regulator first before tearing into the engine ! I kinda doubt it's a rod because if it was a rod it would not get quiet ! to check the regulator pull the hose off and see if gas is in the vacuum hose, there should be no gas in the vacuum hose !

 

I was also thinking fuel regulator, or a bad injector causing that smell. Would that also cause the truck to make that noise? It is drivable, and now it only takes about a second or two for that noise to go away when cold. Other than that, no noise while driving. thanks for your help!

 

I been thinking about what your saying that it quits after awhile and it sounds like it could be a lifter not pumping up right away ! to test the regulator pull the hose off and see if any gas is in the hose, there should no gas in the vacuum hose going to the regulator ! do you smell any gas on the dip stick ? if too much gas got into the oil then it could backfire ! check the regulator first ! if it's ok then it could be a lifter not pumping up right away !

 

Fuel and or coolant in the oil will cause lifter noise, it will also destroy engine bearings.


The fuel pressure regulator is inside the plenum, there is no vacuum line on the regulator. If you suspect fuel in the oil, rather than replacing parts needlessly, check the fuel delivery system. This thread explains: https://blazerforum.com/forum/2nd-ge...eakdown-88305/ Post all 4 readings, and we can help you analyze the results.

 

I will check out the delivery system. Also should note that the fuel pressure is not good on it. A friend of mine tested the pressure out and said it isn't the best. I am really leaning on either the regulator or injector. I did not know it could damage the bearings. thank you all for your tips!

 

you may have more problems than regulator or injector.

 

Yup, if you follow the steps in the "How To" thread, it will give you/us a good idea of what's going on, and if there's a problem.


Oil is a lubricant. Gasoline and coolant will rapidly deteriorate the lubricating ability of the oil, exposing the bearings to the journals, (they should never contact each other). If you're using ethylene glycol, (green) coolant, it has silicate in it, (sand) which is not a good choice as a lubricant. It's also a good reason to use Dexcool coolant, (designed for this vehicle)

 

if you have low fuel pressure maybe the filter is partly clogged up ! sure it can ruin the bearings if enough gas gets into the oil ! I would check the fuel filter, the regulator and change the oil and oil filter !

 

A partially restricted fuel filter will cause low fuel volume, pressure would not be affected. If the filter is totally restricted, there would be zero volume, and zero pressure.