Little problems

[Lavarcarlos]

Oil pressure gauge goes to 0 when I stop and goes back to normal under acceleration. Anyway to easily get to the oil pick up line in the oil pan. Think it's clogged. Also I'd like to lower it. Any suggestions? In the future I'd like to do an engine swap. Would that be a direct bolt situation or would I be getting myself into a world of trouble?

 

[TollKeeper]

Well the oil pressure guage on the 4.2 is fake anyways. It just reads a Yes/No oil pressure, and the ECM mimmicks what it thinks the oil pressure should be.

If you have a guage showing -0-, you should get it checked out. Either your oil pick up screen is blocked, the oil pressure sensor is going bad, or you have a bigger problem.

 

[Ilikemy3s]

Mine did the same thing, turned out it was the OIL Pressure Switch on the side of the block near the filter. Replaced it and all good since.

 

[Mooseman]

Try replacing the pressure switch first. If it doesn't resolve the issue, time to investigate further. Getting the pan off is not an easy job.

 

[Lavarcarlos]

Mine did the same thing, turned out it was the OIL Pressure Switch on the side of the block near the filter. Replaced it and all good since.

On the side of the block near the filter? OK, so it's a pretty straightforward job? I'll definitely give it a try. Thanks

Try replacing the pressure switch first. If it doesn't resolve the issue, time to investigate further. Getting the pan off is not an easy job.

I know this isn't a question either of us really has the answer to, but why in the world did they design this vehicle with the oil pan the way they did?!

 

[Mounce]

What? With the pass through tube? To make it compact enough to fit in the package and still be offered 4wd.

 

[Lavarcarlos]

What? With the pass through tube? To make it compact enough to fit in the package and still be offered 4wd.

That's understandable, but now a damaged oil pan or a clogged pickup line (which I seriously think is my issue) is something like a major job.

 

[Mooseman]

A flush might clean up gunk stuck to the pickup or unstick the oil pump's pressure relief valve. If it's the pump itself, the pickup seal or a really gunked pickup, then yeah, the pan and front cover need to come off unfortunately.

 

[mrrsm]

Before taking the Drastic Action of Removing the Oil Pan & Timing Cover:

(1) Perform an Engine Flush with (6) Quarts of CHEAP Organic Motor Oil and a CHEAP Oil Filter along with One Quart of Engine Flush or Transmission Fluid... BUT Only idling only for around 5-10 Minutes and then change over to using (7) Quarts of Mobil1 and installing a New Mobil1 Oil Filter.

(2) Examine Post #6 via this Thread showing all of the Hardware necessary to Install an Analog Oil Pressure Gauge to absolutely determine the condition and performance of the Internal Oiling System (Oil Pick Up Tube, Gerotor Oil Pump, Working or Non-Working Oil Pressure Sensor):

https://gmtnation.com/forums/threads/testing-the-i6-oil-pressure-without-the-j-42907.15974/

The Video # (2) of this (3) Part Series is a follow-on conducted by @MAY03LT on this very topic. In that segment, Drew uses a Flexible, Black Rubber Quick-Connect Oil Pressure Hose attached to a Large Dial Analog Oil Pressure Gauge to monitor the Engine Oil Pressure directly... instead of using a Copper Line for his apparatus when performing this Test or relying upon the Dashboard Oil Pressure Gauge to figure out what is REALLY happening inside of the running engine.

If the Engine Oil Pressure 'Gollywogs' up and down from a Minimum of (12) PSI down to (0) at idle or fails to rise to around 65 PSI at 2,500 RPM... then this would confirm either Totally Worn Out Babbitt Bearings (unlikely)... a Completely Clogged Up Oil Pick-Up Tube ...or a Failed "O"Ring Seal at the Gerotor Oil Pump Manifold Interface between the Pick-Up Tube and the Oil Pump... or even an Open & Stuck Oil Pressure Relief Valve inside of the Gerotor Oil Pump.

Hopefully, seeing sufficient Positive Pressure on that Analog Gauge when idling and/or raising the RPM will eliminate the worry of causing serious engine damage from having Low Oil Pressure and allow you to focus on changing out the Digital Oil Pressure Sensor, just above the Oil Filter on the Oil Inlet Manifold:

 

[mrrsm]

@Lavercarlos... I'm always attentive when anyone sends me any PMs with concerns that are either private, personal or for any other reasons that involve my misconduct or mistakes here as a GMTN Member... so my response to you here is not meant to discourage your participation via PMs in any way.

But... the issues you brought up in the following message really deserve to be discussed in the Open Forum(s) and if possible... and have them divided into their unique categories, rather than having a whole assortment of problems lumped into one single post that may not stimulate the full responses you need for each one.

The REAL Power and Strength available to you as a Member here at GMT Nation is present because to a large extent... We have a 'Shared Mind" ...One made up from the participation of ALL Members who will read, understand...and if possible... offer you their Best Collective Ideas on how to solve all of these problems:

"OK I have very limited mechanical experience. I mean I can of course change oil, spark plugs, ignition coils and things like that. I even installed the new cam actuator and sensor. Next is going to be the secondary air injection pump and solenoid, but I'm curious to know if the thermostat may be too much for me. Then I had the fan clutch assembly replaced, but I'm still getting the same code. I think it's a 0495 basically a cooling fan malfunction or fan speed too high. What gives. Oh and I'm also getting the 0128 about my engine running too cool. Think my thermostat is stuck open, but I don't know what to start with. Someone was telling me that my problem may be the thermistor or something like that? Any help is welcome. I love my truck and I want to eventually to a engine swap with a turbo. Has anyone ever converted to manual transmission?"

Welcome to GMT Nation... Carlos.... Let's see what your Brothers here at GMTN think that can be done about addressing some or all of what you have concerns about listed below:

(1) Thermostat
(2) Fan Clutch
(3) Code P0495
(4) Code P0128
(5) Thermister
(6) Engine Swap
(7) Turbocharging the GM 4.2L Engine
(8) Exchanging the 4L60E Transmission for a Manual Version

 

[flyinghigh1970]

Oil pressure gauge goes to 0 when I stop and goes back to normal under acceleration. Anyway to easily get to the oil pick up line in the oil pan. Think it's clogged. Also I'd like to lower it. Any suggestions? In the future I'd like to do an engine swap. Would that be a direct bolt situation or would I be getting myself into a world of trouble?

I just experienced the exact symptoms 6 weeks ago,0 psi. at idle,check gauges light and information center saying stop engine but the sound of engine running never changed.My Envoy has no oil leaks so got under it and oil was dripping out the end of the oil pressure switch.Replaced it with a ACDelco switch and haven't had a problem since.

 

[flyinghigh1970]

Ill give my option on the thermostat code,if it was mine I would first be in my Envoy's records looking to see if and when I had changed it last(this is important missing information in the post).If my record showed it hadn't been replaced since I've owned it a new ACDelco thermostat would be getting installed,if it is stuck open it will be visible once you get it off and look at it.I learned from my grandpa how important maintenance records and parts invoices are on your vehicle no matter how small a repair you make.As far as the SAIS and EV fan problems this is the exact reason I just had a PCM tune done to eliminate both systems.

 

[Lavarcarlos]

I kept trying to reply, but it wasn't letting me

 

[Lavarcarlos]

I kept trying to reply, but it wasn't letting me

OK, so is there a way to check the switch? Like a voltage meter? Oh, and could you please tell me exactly where it is? Meant to mention this before, but it only does it after I've been driving for a while

 

[flyinghigh1970]

OK, so is there a way to check the switch? Like a voltage meter? Oh, and could you please tell me exactly where it is? Meant to mention this before, but it only does it after I've been driving for a while

If you have the I6 4.2 its above the oil filter on passenger side close to front of engine.Since mine was leaking oil out the end of the switch I didn't bother trying to test it just went ahead and changed it,if its leaking oil out the end its bad anyway.Ill let someone else explain voltage test it since its just basically a dummy switch as MAY03LT proved.

 

[Mooseman]

Sometimes it fails without any evidence. Without any engine noise, I would try replacing it anyway since it's cheap and easy as suggested earlier.

Thermostat is likely bad and needs replacing. ACDelco or Mahle are good (they are the same). Don't wait too long as this can damage the cat.

What brand did you replace the fan clutch with? Cheap brands and Dorman are usually junk. Our standard answer is to have the PCM tuned and replace the EV clutch with a thermal clutch for a 2008/2009. Hayden is our go to brand whether you stay with the EV clutch or thermal.

If you're replacing the thermostat, replace the temperature sensor at the same time since it's right there and difficult to get to otherwise.

Turbo? Sure. One guy is working on one, another planning on it. A search for threads will yield the info.

Manual? I think it was done a long, long, long time ago over on TrailVoy. Just from this one thread, it's not easy to make it work.
https://forums.trailvoy.com/showthread.php?t=76296
More reading:
https://www.google.ca/search?newwin.....1..gws-wiz.......0j0i10j0i22i30.hEOb7LOZJ7s

 

[Lavarcarlos]

Sometimes it fails without any evidence. Without any engine noise, I would try replacing it anyway since it's cheap and easy as suggested earlier.

Thermostat is likely bad and needs replacing. ACDelco or Mahle are good (they are the same). Don't wait too long as this can damage the cat.

What brand did you replace the fan clutch with? Cheap brands and Dorman are usually junk. Our standard answer is to have the PCM tuned and replace the EV clutch with a thermal clutch for a 2008/2009. Hayden is our go to brand whether you stay with the EV clutch or thermal.

If you're replacing the thermostat, replace the temperature sensor at the same time since it's right there and difficult to get to otherwise.

Turbo? Sure. One guy is working on one, another planning on it. A search for threads will yield the info.

Manual? I think it was done a long, long, long time ago over on TrailVoy. Just from this one thread, it's not easy to make it work.
https://forums.trailvoy.com/showthread.php?t=76296
More reading:
https://www.google.ca/search?newwindow=1&source=hp&ei=reg7XOycAuHajwT9rav4DQ&q=manual+transmission+site:trailvoy.com&btnK=Google+Search&oq=manual+transmission+site:trailvoy.com&gs_l=psy-ab.3...70.8886..9428...0.0..1.360.5181.5j21j7j1....2..0....1..gws-wiz.......0j0i10j0i22i30.hEOb7LOZJ7s

Thanks for all the info... I just got done reading the thread over on trailvoy concerning manual transmission and it seems like an awesome hassle. I'm waiting on the oil pressure switch and thermostat now. Didn't think about the temperature sensor. Guess I'll order that too. Again, thank you. Don't crucify me, but I came up working on imports and honestly this is my first domestic and I love it. Just wish I knew more about it. I know it's an i6, but is there a kit or something that would allow me to have "true" dual exhaust? Versus splitting just before the resonator or Mufflers? Sorry to be asking so many questions, but it's not easy finding this info simply using Google. Could you give me a link or two for sites that carry trailblazer goodies? Thanks again for all you guy's help!

 

[Mooseman]

There are lots for the V8 flavour but all I've ever seen was this one from Magnaflow.
https://www.ebay.ca/itm/2002-2010-Chevy-Trailblazer-4-2L-Magnaflow-3-Cat-Back-Dual-Exhaust-System-16833/121184530153?fits=Model:Trailblazer&hash=item1c37292ee9:g:c0sAAOxyAs9SOx-o:rk:23f:0&vxp=mtr

Our exhaust is already pretty free flowing. I had gotten a JBA Headers cat-cack system, which was 3" (vs. 2.75"). Although it was nice, it made the TB sound like a fat ricer. I've got a thread here somewhere on it with different mufflers.

There are headers also available but the gains are questionable, same as the exhaust.