69FJ40 dipstick tube leak (1 Viewer)

[Do Over]

Due to a lot of time fixing PO Specials, I haven’t had a lot of drive time. Yesterday I got a chance to go for a good romp. This morning I realized I had a pretty good oil leak. Dried everything and then rev’d the engine to 2000 and held long enough for the leak to appear. Sure enough, a good size pool formed at the bottom of the dip stick tube. Dried things and looked specifically at that since I had replaced the tube. Turns out oil was coming out the top of the tube. The dip stick isn’t even close to sealing. Temporary used clear tubing to check. See below. Quite a bit of oil comes up in the tube. Is this normal and should I expect a new dipstick to correct the problem?

 

[flee]

Sorry to be the bearer of possibly bad news but it isn't the dipstick.
Either the PCV system isn't venting properly or you have serious blowby.
In my case it was the latter. I had almost no compression in 2 cylinders.
A compression check will diagnose after checking that the pcv is operating correctly.

 

[Do Over]

Sorry to be the bearer of possibly bad news but it isn't the dipstick.
Either the PCV system isn't venting properly or you have serious blowby.
In my case it was the latter. I had almost no compression in 2 cylinders.
A compression check will diagnose after checking that the pcv is operating correctly.

No PCV. PO put a vent on the side of the oil fill and one on the valve cover. Checked compression a month ago. It wasn’t great: 114 to 128psi but no big drop between adjacent cylinders. Now I guess I will go back and do a wet test.

 

[Do Over]

No PCV. PO put a vent on the side of the oil fill and one on the valve cover. Checked compression a month ago. It wasn’t great: 114 to 128psi but no big drop between adjacent cylinders. Now I guess I will go back and do a wet test.

Just went and checked the two breather filters. One on the oil fill was dry. The one on top of the valve cover was saturated with oil and had some “shredded” plastic pieces in it. Noticed some fumes coming out of the vent.

 

[Dizzy]

So, the breather on the valve cover is fine, minus the plastic.

Normally, you need a PVC valve on the crank case. It is there to draw up, a metered amount, of gas into the intake manifold. The one on the valve cover is to draw filtered air into the crank case.

 

[Dizzy]

In other words, you need negative pressure in the crank case to keep the oil out of the dipstick sleeve. Your compression sounds good. Mine is barely triple digit, and the engine runs tight.

 

[middlecalf]

Following. So what did the early rigs without a pcv system do to alleviate crankcase pressure? My ‘63 doesn’t have a pcv system (just vent on valve cover) and I’m also getting oil out the top of my dipstick tube. My cylinder compressions are 135 to 150.

 

[flee]

Following. So what did the early rigs without a pcv system do to alleviate crankcase pressure? My ‘63 doesn’t have a pcv system (just vent on valve cover) and I’m also getting oil out the top of my dipstick tube. My cylinder compressions are 135 to 150.

A functional pcv system will help reduce crankcase pressure.
But worn rings, cylinders and guides can give OK compression readings and still allow enough exhaust blow-by to pressurize the crankcase.

 

[Living in the Past]

No PCV. PO put a vent on the side of the oil fill and one on the valve cover. Checked compression a month ago. It wasn’t great: 114 to 128psi but no big drop between adjacent cylinders. Now I guess I will go back and do a wet test.

The vent on the oil fill is designed to be under a vacuum not just vent to the atmosphere. The vent on the valve cover just being vent to atmosphere is fine. PCV stands for positive crankcase ventilation. Line running to the intake manifold guarantees a flow out of the crankcase. Just vented the crankcase will be under pressure and the dip stick is lower then the vent off the oil fill and will leak..

Following. So what did the early rigs without a pcv system do to alleviate crankcase pressure? My ‘63 doesn’t have a pcv system (just vent on valve cover) and I’m also getting oil out the top of my dipstick tube. My cylinder compressions are 135 to 150.

FJ25 had a vent tube (draft tube) off the oil fill. Have to know where to look but the valve cover had a couple of slits for air to enter. The end of the draft tube was located in a matter that while moving air rushing by the end of the tube would cause air to be drawn out of the crankcase. Obviously the the best system but that is what they had.

 

[middlecalf]

@FUTURE MUDDER do you have a pcv valve on the oil fill tube? My ‘63 doesn’t, it looks like this pic in my 1966 F-engine repair manual which doesn’t show or mention anything about pcv system. Frustrating.

 

[Do Over]

@FUTURE MUDDER do you have a pcv valve on the oil fill tube? My ‘63 doesn’t, it looks like this pic in my 1966 F-engine repair manual which doesn’t show or mention anything about pcv system. Frustrating.
View attachment 2478121

It might have had at one time. Now there is a 90 degree bend fitting off of the oil fill tube. This fitting has a cone shaped filter on it. Please see the attached photo. You can see the filter next to the oil fill. I have a Weber carb. I don’t think there is an attachment point for for a line from a PCV valve.

 

[Living in the Past]

@FUTURE MUDDER do you have a pcv valve on the oil fill tube? My ‘63 doesn’t, it looks like this pic in my 1966 F-engine repair manual which doesn’t show or mention anything about pcv system. Frustrating.
View attachment 2478121

Does your valve cover have the vent tube. If it does it had a PCV at one time. Have two 1961 FJ40 project vehicles. One has the PCB and other can see where it was on the oil fill. Have a parts vehicle that is 62 production. Would have to check if the the oil fill tube is there. I know manifolds and distributor is missing. Valve cover has the vent tube.

Here are a few pictures I had from earlier this year.

 

[Do Over]

Does your valve cover have the vent tube. If it does it had a PCV at one time. Have two 1961 FJ40 project vehicles. One has the PCB and other can see where it was on the oil fill. Have a parts vehicle that is 62 production. Would have to check if the the oil fill tube is there. I know manifolds and distributor is missing. Valve cover has the vent tube.

Valve cover does have the vent port. That now has a cone shaped vent just like the one shown in the photo next to the oil fill.

 

[Dizzy]

Under the Weber air cleaner assembly is a hole for the PCV inlet. That would go to the valve cover where the cone filter attaches. There is a baffle inside the valve cover. It isn't a nice routing, but, most have made it work. I've considered a Weber, and thought that I would use a bit of custom bent hard line for this.

The PCV valve normally attaches to the push rod cover, internally baffled (probably to address the oil that is flung around by the crank itself), on later models. There would be a hose that runs to the manifold, not the carb (unless it is the adapter plate). There appears to be a manifold cap on the front driver side intake. I don't know if a later push rod cover would get you an clean install on the PCV valve?

The OEM Toyota PCV valve is my go-to for correct metering of crankcase gasses. It might change the tune of your carb a bit leaner.

The PCV valve on my '75 will collect emulsified oil, as moisture in the blow-by condenses here. It is a bit of a rust thing, but with regular maintenance, it will reduce sludge formation.

 

[middlecalf]

@FUTURE MUDDER both of those cone shaped filters are not original. The PO was using those to keep unwanted stuff out of the engine, a noble purpose. The plastic bits are disconcerting, and I have no clue as to what and from where.

So there’s a lot misinformation available wrt engine venting, and I’ve struggled with this on my build a great amount. One of the contributors is there were options available for this venting and the applicable years also comes into play. And the use of existing vehicles’ parts as an explanation is always subject to originality.

Here‘s some info/Picts from a ‘65 parts book, 04 Engine Group. First the valve cover (C) - there is only one pict shown and it is without a vent (tube). But the associated parts listing shows 7 different part numbers. My guess is that the OPT with English one is the optional vented cover for US market.

Looking at the air cleaner, there are two types, a dry paper filter and an oil bath filter. I only show the oil one because it’s the only one with the hose (D) that connects to the OPT vented valve cover. What‘s important is that the valve cover vent is connected to the air cleaner unit that pulls are in, so it’s not a fresh air vent but a forced air evacuation. Because it’s before the carb it’s not a vacuum leak source being unchecked by a valve. On another note, the valve covered volume and the crankcase are at the same atmospheric pressure (within small time increments) because they are connected via the lifters and valve rods passageways - necessary for valve rocker oil to return to the crankcase. So there is some crankcase pressure reduction due to the valve cover vent when properly connected to the air cleaner. But as far as anti-smog enthusiasts... (next up PCV)—>

Now to the PCV, or rather correctly, the optional anti-smog system. It’s possible that in ‘69 this was no longer an option but standard, I don’t know but someone with access to a ‘69 parts book would know. Of note here in any case is that the ventilation valve output is connected to the manifold after the carb, hence the need to have the check valve to prevent a vacuum leak source. So when the pressure on the valve side is greater than the pressure on the manifold side, air is pulled into the manifold. Nothing (should) happens if the opposite occurs.

So now the questions - what to do if you don’t have a PCV, don’t have a valve cover vent, or have one of either (my case, just the vent cover), or both (as in your case). And that we both have oil coming out of our dipstick tubes at the top. Someday someone will figure this out.

Over. Good luck.

 

[middlecalf]

So with that diatribe here’s what I’d do in your case @FUTURE MUDDER . I’d connect up the oil fill tube to a manifold location after the carb, with a valid PCV valve at the oil fill boss. And keep the triangle filter on the valve cover vent since you don’t have the original air cleaner, and just occasionally clean the filter. Hopefully that stops your leak. Maybe do some additional tests - leak down and vacuum - as well and assess whether you need to address the source of the pressure in the crankcase. GL.

 

[Do Over]

So with that diatribe here’s what I’d do in your case @FUTURE MUDDER . I’d connect up the oil fill tube to a manifold location after the carb, with a valid PCV valve at the oil fill boss. And keep the triangle filter on the valve cover vent since you don’t have the original air cleaner, and just occasionally clean the filter. Hopefully that stops your leak. Maybe do some additional tests - leak down and vacuum - as well and assess whether you need to address the source of the pressure in the crankcase. GL.

I think middlecalf has hit on the solution. According to the attached from Haynes, it should work that way. According to the write up, a faulty PCV valve will affect the engine idle speed as well as giving poor fuel economy and acceleration.

NAPA had the PCV valve for $4.39. Thanks for the help, all of you.

 

[Do Over]

I think middlecalf has hit on the solution. According to the attached from Haynes, it should work that way. According to the write up, a faulty PCV valve will affect the engine idle speed as well as giving poor fuel economy and acceleration. View attachment 2478501NAPA had the PCV valve for $4.39. Thanks for the help, all of you.

Now that I reread it, that’s what Dizzy told me too.

 

[middlecalf]

But Dizzy was way more efficient with his words!

I like that Haynes manual pic, but I still wonder how that fresh air gets in from the air cleaner when the motor is running. There’s a lot of sucking from the carb, but maybe the top side of the moving valves generates a fair bit of positive pressure in the valve rocker area.

 

[Living in the Past]

But Dizzy was way more efficient with his words!

I like that Haynes manual pic, but I still wonder how that fresh air gets in from the air cleaner when the motor is running. There’s a lot of sucking from the carb, but maybe the top side of the moving valves generates a fair bit of positive pressure in the valve rocker area.

The PCV is really just a one way check valve. If the valve cover is positive most likely because the valve stems are leaking or PCV is plugged causing a positive pressure in the crankcase and fumes coming up around the push rods. Today this is part of the emissions. Prior to emissions it prevented a gas/air mixture from exploding in the crankcase. Bad enough blow by as the fuel/air in the cylinder ignite and leak by the rings and explode in the crankcase. The draft tube on the oil fill was designed to remove the fumes. The PCV was just more efficient using the vacuum in the intake to draw it out.