How to: 4.0 OHV Refresh

[97Sandbox]

Just askin' since I haven't seen it mentioned.

Have you pulled the dipstick or better yet drained the oil to see if anything is going on down there?

Loss of oil or milkshake?

Yep, I've checked many times because oil in coolant to me points to blown head gasket and I'd expect coolant in oil too.

However, the oil on the dipstick is clean and still at the level it was when I changed it a couple months ago (second hole on the dipstick). No milkshake on the inside of the fill cap either.

I'm not trying to rationalize myself out of the possibility of a blown head gasket, I'm just struggling to find anything unusual except oily gunk in the cooling system. Any other checks I should do before I chalk it all up to years of grime that just happened to come loose during the flush?

 

[97Sandbox]

To add to that last post, only thing I haven't done is drain the oil, but given how clean the dipstick looks, I'm feeling okay. I can probably drain a quart or so just to check if there's any water hiding at the very bottom of the oil pan.

 

[Lee's Automotive]

To add to that last post, only thing I haven't done is drain the oil, but given how clean the dipstick looks, I'm feeling okay. I can probably drain a quart or so just to check if there's any water hiding at the very bottom of the oil pan.

Have you did a chemical flush?

 

[Explodemylifepls]

Flush it with dawn dish soap. Ik you said it can't be ATF but if it WERE ATF I've had to use dish soap to get it out of the radiator before, maybe It will work with your oily sludge.

 

[97Sandbox]

Have you did a chemical flush?

I did a chemical flush back when I wrapped up reassembly after the initial "refresh." My goal was to clean out the crud that I saw in the cooling channels of the heads but couldn't remove with just the intake manifold off. After I drained the chemical flush/water mix, I ran a round of distilled water through the system, then replaced that with a 50/50~ish distilled water/antifreeze mix.

Are you thinking I should do another chemical flush, or do you think the flush might have loosened up the oily stuff I'm seeing now?

Flush it with dawn dish soap.

This is a solid idea. If the crud doesn't come back after a soapy flush, I can probably conclude it was just built up gunk. But if the oil still comes back, it might be time to try a leakdown test to 100% check the head gaskets.

 

[donalds]

It is almost impossible to remove all of the coolant from your engine lots of it is up in the heads Just a thought
Have you ever seen an engine on a stand and then they rotate it and all the fluid pores out even though it has previously been drained

You may just be getting that fluid
drive it for a little while and then drain and refill check then

 

[97Sandbox]

It is almost impossible to remove all of the coolant from your engine lots of it is up in the heads Just a thought
Have you ever seen an engine on a stand and then they rotate it and all the fluid pores out even though it has previously been drained

You may just be getting that fluid
drive it for a little while and then drain and refill check then

Yeah, that's what I'm starting to suspect.

I'm likely going to keep running it with the distilled water that's in it now and the thermostat removed (at least until I get a new thermostat with the bleeder feature). Hopefully any residual crud flushes out when I drain the system to install the new thermostat and refill with coolant mix.

 

[97Sandbox]

This is a solid idea. If the crud doesn't come back after a soapy flush, I can probably conclude it was just built up gunk.

After some further reading, I've concluded Dawn in the cooling system is NOT a good idea. Some suggest a non-foaming detergent (e.g. Cascade) can work, but ultimately these detergents are corrosive to aluminum and not a good idea to have running through a radiator unless you really need to clean out serious oil contamination. I'm not sure the degree of oil contamination I'm seeing warrants taking the risk.

 

[donalds]

The biggest thing I would be worried about is the water pump seal
What will hurt the water pump seal

 

[97Sandbox]

Drained some oil from the pan:

Looks like typical used oil to me, no sign of coolant.

If I understand correctly, the only way I'd be getting oil/coolant mixing from a blown head gasket but pass a compression test would be if the head gasket is solid between cylinders but blown between a coolant path and an oil drain hole. Since coolant is under pressure and the engine is not, I'd expect more coolant in oil than oil in coolant. Am I wrong in thinking all signs point to good head gaskets and the oil in the cooling system had to come from somewhere else?

 

[fast_dave]

Grant -

Just trying to offer some perspective here.

Don't put too much emphasis on a cold engine compression test being the ultimate tell-all of a head gasket problem.

Some head gasket problems don't show up until operating temperature (and beyond) has been reached - especially on 90's high operating temp smog motors.

At this stage, you've done coolant system flushing and replacement of the thermostat.

That said, that pic of the slime in the radiator neck is alarming to me.

All I can see left is to mark your overflow tank with a "sharpie" horizontal line and IF YOU CAN daily drive your Ex, carefully checking the coolant level in the tank every morning when it's cold.

Over the course of a week or two, if you discover the use of coolant, no matter how mynute/slight, that will confirm to you that you have a problem.

At first you'll probably think to yourself "oh - it's just the coolant level balancing as air is released" BUT you'll find that every two weeks you're still losing & adding coolant...

ALSO, a head gasket issue will only worsen to the point where the engine will eventually misfire/buck.

As an aside; Band- Aid head gasket fixer liquids, IMHO, are just that; band aids waiting for the "right" inconvenient moment to fail.

There's only one correct way to fix a head gasket on a 20+ year old vehicle that operates at these high temperatures.

HTH and your mileage may vary -

 

[97Sandbox]

Thanks for the input, Dave. Once I get the new thermostat in and add the coolant mix, I can definitely drive the truck more and monitor the coolant level.

I can also do a hot/warm compression test, but I thought a cold compression test was worst case scenario?

 

[410Fortune]

Could it be lower intake gasket issue?

 

[fast_dave]

Thanks for the input, Dave. Once I get the new thermostat in and add the coolant mix, I can definitely drive the truck more and monitor the coolant level.

I can also do a hot/warm compression test, but I thought a cold compression test was worst case scenario?

Grant,

These tests work for the 80 percentile.

Every once in a while you have a engine that for some reason is an outlier.

Yours obviously has a problem - as shown in the picture and the flush pictures.

I'll even complicate it - your problem could also be OHV Head Related = Micro Cracking

Sometimes they don't show up until the head is running at temperature and under actual combustion.

 

[fast_dave]

Could it be lower intake gasket issue?

Could even be this.

The Factory/OEM Original OHV style intake gasket is a one-piece stamped aluminum valley type gasket.

The aftermarket intake gaskets are not this valley type stamping, but rather two separate gaskets that sit JUST on the heads.

Torque differences, height differences, differences I'm not thinking about.

The plot thickens

 

[97Sandbox]

At least lower intake gaskets would be way easier to replace than head gaskets. I'm running the two-piece Mahle gaskets with their special silver silicone in the valley. I tried my best to hit the torque specs in my service manual and follow the advice folks posted here but who knows.

A small crack in a head would make sense too especially if the crack is only opening up when the heads get hot and expand.

I'll keep running the truck and monitoring for more oil in the radiator and consumption of coolant.

 

[fast_dave]

At least lower intake gaskets would be way easier to replace than head gaskets. I'm running the two-piece Mahle gaskets with their special silver silicone in the valley. I tried my best to hit the torque specs in my service manual and follow the advice folks posted here but who knows.

A small crack in a head would make sense too especially if the crack is only opening up when the heads get hot and expand.

I'll keep running the truck and monitoring for more oil in the radiator and consumption of coolant.

Hey Grant -

I get it and feel your pain - you have one of those outlier problems that really gets the brain juices flowing.

In my mind, it's a hot engine / under pressurization problem BECAUSE it's pushing oil into the coolant, but not sucking coolant back into the oil.

To clarify, you're showing what appears to be oil in your radiator neck, but when you drain your pan oil we don't see a water/oil separation line.

This gets me thinking is either head gasket (beginning to fail meaning a small failure) or a head crack.

I hope that makes sense.

 

[97Sandbox]

It does make sense. That's actually why I used the phrase "mildly blown" head gasket in the post with the radiator gunk.

So far I've driven 30 or so miles today, no oil has surfaced in the reservoir and the water level has not dropped. Of course I'm still running without a thermostat for now so I'm only reaching a hair over 150F. It'll be very interesting to see how it all goes once I drain the water and install the new thermostat (ETA Friday 8/5).

 

[97Sandbox]

All mechanical issues aside, it's a beautiful day here in Wisconsin, I got a great haul for $35 at the local salvage yard, and I'm thoroughly enjoying driving/maintaining/modifying this Sport. Always work to be done, but gotta savor the little victories.

 

[fast_dave]

After my top end rebuild with rebuilt OEM heads (but not my Ex's original heads that were turned in for a core charge), I was good for around two months.

At first I checked the oil every day for a week or so.

Not seeing any oil use, I spread it out to every week or two.

Then, from what I remember, one day while checking the oil level, I noticed slight coolant loss in the overflow tank.

Then, I started to notice smelling coolant in the cold start exhaust.

Kept a close eye on it - and remember that it took two weeks of daily driving before it was really noticeable too see the coolant move off of the witness mark about 1/8" on the overflow tank.

Given how wide and long the overflow tank is, I believe I measured it was using about 2 ounces every two weeks.

Then the misfiring started - first at cold start, and then after about a week or two it was through out the day.

In the end, I never figured out if it was cracked heads OR a crack in the cylinder wall that went into a water jacket

Truck had 215,000 miles, and I needed a daily driver - so off it went to the wrecker.

I miss my 2 Door 4WD that I named "Hank the Tank" -

Nothing better than manually shifting your gears, A/C cold as the Artic, and parking wherever the F I wanted.

A true urban assault vehicle for the PRK that flew under the radar...