1988 ranger. Compression confusing and other issues

[NateWollzie]

Hello all! New to Ranger nation.. but I have a 1988 Ranger.. 2.9L.. was told 160k but I know it's probably 260k on the milage lol.. anyway, I had a crank no start issue recently and traced it back to a severed electrical ground in the fuel system circuit.. now that I got her running... More problems.. fuel pressure was decent both times I last checked.. the oil pressure climbs when you first start it.. levels out when warm.. but spudders and/stalls occasionally.. also noticed smoke coming from from exhaust manifold/valve cover or engine idk lol I'm not a mechanic.. spark plugs extremely gunked up and oily.. and my compression is low on all cylinders unless I crank the engine for about 8 seconds I can get normal compression. I'm at around 90psi on all cylinders cracking for 5 seconds. glove test on the radiator and nothing.. temperature gauge fluctuates.. spark plugs get extremely hot but no overheating.. doesn't seem like I'm losing coolant but definitely losing oil... not sure if that's normal. I feel like my head gasket may be blown. Any thoughts would be appreciated!! Thanks in advance

 

[RonD]

Welcome to TRS

When you do a compression test all spark plugs must be removed so you get good cranking speed
Battery voltage should be 12.4v to 12.8volts, for the same reason
Press gas pedal to the floor and hold it down when cranking, this is to get good air flow into the engine
And yes, longer crank time, 10 to 12 seconds, you need to "hear" 5 to 7 "hits" of the compression stroke from the cylinder being tested, you will hear it

Expected compression on the 2.9l is 150psi, at sea level and new, lol
In Idaho with the higher elevation compression will be lower
And with higher miles it will be lower but I would expect 135-145psi

On each intake valve there is a valve guide seal inside the valve spring in the valve cover area
Vacuum in the intake manifold is about 18" of negative pressure, this will cause oil to be sucked in from intake valves valve stem if the seal is worn out
The oil is then sucked in to the cylinder when valve opens
This is the most common way oil gets into cylinders
The PCV Valve combats this oil being sucked in, so it needs to be in good working order
PCV Valve should be changed every 3 oil changes, and its hose cleaned out, also the Breather hose
PCV Valve creates negative pressure in the valve cover area which means less oil would be pulled down the intake valve stems

On older engines like the 2.9l, people often install a Catch Can on the PCV Valve hose, this reduces the amount of Blow-by oil vapor being sucked into the engine
On all piston engines, new or old, each time a cylinder fires some of the HOT gases will "blow by" the piston and rings and into the crank case
As any engine ages the amount of blow-by increases, this is normal
The HOT blow-by will vaporize some of the oil on cylinder walls and piston sides, this is the ONLY place in the engine that can create oil vapor, bearings and valve train never get hot enough to vaporize oil
Most of the oil vapor stays in the crank case area but it is hot so some of it "rises" thru the drain holes in the head and into the valve cover areas
This oil vapor is then sucked in thru the PCV Valve and into the intake and then into the cylinders
A Catch Can is used to try and cool down the oil vapor so it condenses in the can, so it is not sucked into the intake

Using a higher grade oil can also reduce the oil vapor in the engine, it doesn't vaporize as much as lower grade oil

Burning oil is not great for the spark plugs or the exhaust system, lol, I know DUH
So you may just need to clean them more often and check out and refresh PCV system

To test if Valve guide seals are leaking, and AFTER new PCV Valve
After engine is warmed up, coast down a hill IN GEAR, this creates a HIGH Vacuum in the intake
At the bottom of the hill press down on gas pedal(still in gear) and watch tail pipe emissions
If you see a puff of smoke valve guide seal are leaking, the bigger the PUFF the bigger the leaks

 

[Shran]

Welcome to the forum!

First off, gauges in first gen trucks (83-88) were notoriously inaccurate. I have put aftermarket gauges in just about every single one I've owned... I do not trust them. That could and probably does account for gauge fluctuations that seem weird.

The smoke issue from the valve cover area is probably oil leaking out of the bottom edge of the valve covers and onto the exhaust. Very common on these trucks, fairly easy to fix if you have AC, very easy to fix if you don't.

90psi is really, really low. What number do you consider "normal?" 90 is about the minimum for a gas engine to run at all... I would add some oil to each cylinder and redo your test, maybe with a different gauge, something is not right and I suspect your actual numbers are much higher than 90psi if it runs at all.

Spark plugs should get hot, by the way, lol

 

[NateWollzie]

I was getting mixed information about the compression test.. I pulled all plugs, was told to cut power to the fuel system and I went with unplugging the inertia switch.. I was also told to hold the throttle open and crank the engine for 5 seconds.. I tested it on one, did 5 seconds and got 90psi, turned the key 8 or so seconds and 5 "hits" and was around 120 psi in cylinder 1. I will redo the test on all 6 and share my results. There is most definitely an oil drip that im unable to find the source of bit the area under the vavle cover is cake with oily gunk, down around the plugs. I cleaned them up as best I could with everything will assembled.. I was starting to think it may have been the head gasket.. I will swap out the PCV valve, re test and drive it tomorrow to watch for oil. I thank you both for sharing your knowledge.. she's a little beat up and dirty with lots of issues and I'm no mechanic.. But it keeps my mind occupied and I'm determined to spruce her up! Ps no AC and yes I know spark plugs should get hot.. But it feels a bit excessively hot under the hood

 

[NateWollzie]

So in all, I will replace the pcv for the idle issue and the vavle cover gasket for the oil leaking down by the spark plugs... Before the cake gasket I'll compression test the proper way and share results thank you

 

[NateWollzie]

Welcome to TRS

When you do a compression test all spark plugs must be removed so you get good cranking speed
Battery voltage should be 12.4v to 12.8volts, for the same reason
Press gas pedal to the floor and hold it down when cranking, this is to get good air flow into the engine
And yes, longer crank time, 10 to 12 seconds, you need to "hear" 5 to 7 "hits" of the compression stroke from the cylinder being tested, you will hear it

Expected compression on the 2.9l is 150psi, at sea level and new, lol
In Idaho with the higher elevation compression will be lower
And with higher miles it will be lower but I would expect 135-145psi

On each intake valve there is a valve guide seal inside the valve spring in the valve cover area
Vacuum in the intake manifold is about 18" of negative pressure, this will cause oil to be sucked in from intake valves valve stem if the seal is worn out
The oil is then sucked in to the cylinder when valve opens
This is the most common way oil gets into cylinders
The PCV Valve combats this oil being sucked in, so it needs to be in good working order
PCV Valve should be changed every 3 oil changes, and its hose cleaned out, also the Breather hose
PCV Valve creates negative pressure in the valve cover area which means less oil would be pulled down the intake valve stems

On older engines like the 2.9l, people often install a Catch Can on the PCV Valve hose, this reduces the amount of Blow-by oil vapor being sucked into the engine
On all piston engines, new or old, each time a cylinder fires some of the HOT gases will "blow by" the piston and rings and into the crank case
As any engine ages the amount of blow-by increases, this is normal
The HOT blow-by will vaporize some of the oil on cylinder walls and piston sides, this is the ONLY place in the engine that can create oil vapor, bearings and valve train never get hot enough to vaporize oil
Most of the oil vapor stays in the crank case area but it is hot so some of it "rises" thru the drain holes in the head and into the valve cover areas
This oil vapor is then sucked in thru the PCV Valve and into the intake and then into the cylinders
A Catch Can is used to try and cool down the oil vapor so it condenses in the can, so it is not sucked into the intake

Using a higher grade oil can also reduce the oil vapor in the engine, it doesn't vaporize as much as lower grade oil

Burning oil is not great for the spark plugs or the exhaust system, lol, I know DUH
So you may just need to clean them more often and check out and refresh PCV system

To test if Valve guide seals are leaking, and AFTER new PCV Valve
After engine is warmed up, coast down a hill IN GEAR, this creates a HIGH Vacuum in the intake
At the bottom of the hill press down on gas pedal(still in gear) and watch tail pipe emissions
If you see a puff of smoke valve guide seal are leaking, the bigger the PUFF the bigger the leaks

I was able to charge the pcv valve and the grommet this evening and the idle improved drastically. After a minute or two it started to jump and spudder like it wasn't getting gas.. gave it a couple pumps and it was idling smoothly.. We're off to a good start! I'll check fuel pressure and compression tomorrow evening

 

[Rimjam]

My little '88 with a 2.9 had chronic small valve cover leaks until I went to NAPA & paid $55 for their 'Blue' gaskets - problem solved.

 

[NateWollzie]

My little '88 with a 2.9 had chronic small valve cover leaks until I went to NAPA & paid $55 for their 'Blue' gaskets - problem solved.

I'll look into it, thank you! Think I'm going to go ahead and break her down.. change the head gasket, check the internals, clean the block up because I'm pretty sure there's about a half inch of oil gunk and mud on it lol. Guy before me didn't know how to wash a truck

 

[Shran]

The "good" gaskets are Felpro Permadry, think they're about $35 on Rockauto.

I wouldn't put too much effort into changing head gaskets. Valve covers, yes. Head gaskets rarely fail on these engines, it's the heads themselves that fail first.

Usually for cleaning up engine bays I will grab a gallon of citrus degreaser, mix it 50/50 with water and use a cheap pump style weed sprayer to hose everything down under the hood, then hit it with the pressure washer or car wash. May take several tries but even a really nasty engine bay usually comes out pretty clean.

 

[NateWollzie]

Alright perfect! I am hesitant on pressure washing the engine bay due to the wiring catastrophe.. courtesy of the owner before myself.. but my fuel pressure was around 45 psi. Still haven't had a chance to test compression.. it's 102 degrees lol but while wiping some things down I noticed the bolts to the valve cover were nowhere near tight... It's running very well compared to yesterday...
Another question.. so looking at the engine bay, the pcv valve is located on the left hand side.. now on the right hand side, about the same location as the pcv, i also see a similar plug valve type thing that's pushed into a grommet similar to the pcv.. it is circular and black.. what is this piece? The grommet on my pcv was very worn out as well as this other circular black pieces grommet.. it also looks as if it is cracked. Just can't figure out what it is lol

 

[RonD]

PCV systems have two parts/hoses

On a "V" engine the PCV Valve and its hose will be on one valve cover
The "breather" hose will be on the other valve cover, it will go from valve cover to air filter or air plenum(tube from air filter to engine)

This allows PCV to pull in fresh "filtered" air when engine is running or if PCV gets clogged blow-by will come out breather and be sucked into engine that way

 

[NateWollzie]

Yes Ron I understand the pcv valve now, I looked into it's functions after you told me to check it out.. this is a separate piece, on the other valve cover, on the opposite side of the pcv.. it's the same grommet as the pcv but it is circular, black and has a hose running to the throttle body.. I think. I will take a photo and post it. Thank you Ron