I have been searching around the forum and gotten a bit of info but wanted to put my story out there for further comment.

Coolant level seems to have dropped quite quickly. Upon checking oil I see the foam type situation under the oil cap. There also seems to be similar on dip stick. As most would I assumed it was probably a head gasket issue, however, after some reading on this particular vehicle I understand it could be something else. In particular I saw some comments about the following possible problems (other than head gasket):

1. Water pump?
2. Oil pump?
3. Timing chain/guides

Actually the timing chain guide thing sounds interesting although I am just not sure how to check for this. It sounds like the guides can break and then the chain wears through something whereby then water can leak in with oil.

Anyways, my first thought was to try one of those hg sealers but when I started reading about some of these other possible issues I assume it would make sense to check them out first. Any suggestions on where I can find info on how to check the other possibilities. For reference my vehicle is a 1990 22RE std transmission with almost 450,000 km (280,000 mi). Words of wisdom much appreciated.

22RE does have timing chain guide failures, my brother's '95 went out, particles killed the radiator and water pump. It made a bit of noise prior so he had warning, but didn't take action and ended up with a replacement motor and radiator.

In your position I'd stop driving and get it apart pronto to see what has failed. Agree that it is likely head gasket as that will mix oil and coolant. Put in a fresh water pump and chain guides while you're in there. ��

Thank you for the advice. I also watched some videos today on replacing some of these things (head gasket and timing chain). Although this vehicle is supposed to be easier than many, it sure looks like lots of work. But maybe isn't worth doing unless I do it myself. Then the question becomes - can I? I putter around with my vehicles in doing some mtce items (eg. oil changes, alt replacement, brake replacement) but never anything this big. I guess I could look at it as therapy

Can you do a compression test on the engine? That would help confirm or deny the head gasket theory

Check the timing chain guides by pulling the timing cover.

Sound like ether way this engine is coming apart.

The mileage you have on te truck is getting up near the end of the expected life of a 22RE. They are very stout engines, but of course they do wear out. My point is, if you are going to tear it apart to do a HG replace, you probably should get the head rebuilt, and if you dont have the skills and equipment to do that, its not that expensive, there are head shops out there which do it.

With the head off, I would replace the timing chain and guides, and potentially the sprockets if they are worn. When it goes together, you should put a new water pump in it.

If you have access to a cooling system pressure tester, you can use that to see if its a compression (head gasket) leak, the pressure gauge needle will vibrate due to the compression leaking into the cooling system. If there is no compression leak, and only a water jacket leak, its still probably a HG....but as someone else observed, the timing chain guides can wear to the point where the chain eats into the water jacket.

Good luck w/ it.

Another thing I don’t see mentioned about coolant being in the oil is that as soon as coolant appears in the oil you need to stop driving immediately. It really doesn’t take long at all for coolant to destroy your crank bearings. They can turn them to brass within a few minutes.

Thanks for the advice. I understand there might be a couple tests to confirm HG - compression (via the plugs) or what about the gas? test at the radiator (I have seen something on that before). Is there a preferred/better method of test? Yes, I think engine is probably getting near the end. Given that no matter what was at fault at the moment (HR or maybe chain related) it would be best to do most of it if I were to start taking it apart.

Thanks for the advice on all the pieces that should be replaced. If I were to try and tackle this it sure would be nice to have a garage (I usually just do my work on the driveway). Anyways, do you happen to know where best place is to get some of these parts - timing chain and related parts (with the metal as opposed to plastic guides). I saw many pointing to engnbldr.com, however, it seems they are no longer in business.

Yes, I did stop driving. Not sure how long it went like this. I did just add a little oil less than a week ago and didn't notice the buildup on inside of oil cap (although maybe I just didn't see it). At this point maybe i should drain the oil to see what it looks like. thanks again for the advice.

Do a pressure test on your coolant system. Look for leaks. Note the psi every 5 minutes starting at 20 psi depending on how fast the leak can tell you a lot. Also a compression test of the cylinders. If you have coolant in a cylinder it will come out the blow out valve during a compression test this if this is the case it’s definitely a blown head gasket.

Should I be able to confirm whether the timing chain guides are toast by opening up the valve cover and looking down rather than removing the timing chain cover (which I believe would be more complex).

Here is what I have done so far:

1. drained the oil and refilled - clearly it has water/coolant in it.
2. topped off the radiator with premix - it took about 1 US gal.
3. rented the combustion leak tester and did a test at radiator (blue fluid).

After the truck ran for a short while (there was initally a fair bit of white smoke out the back) I started with the combustion leak detector - squeezing for several minutes. The fluid did not change colour at all (remained blue). However, when i removed the tester there was a lot of oil/water mix now at the top of radiator. I shut it down for a minute and started up again to do more of the testing (thinking maybe it hadn't heated up enough). Tested for a few more minutes - test liquid remained blue.

I had assumed it was only coolant getting into oil, however, it appears to be going both ways (coolant into oil and oil into coolant).

So what does this all likely mean? Could it be that the block/hg are ok and that it is the timing chain issue (rubbing through the water jacket) - would this cause the oil/water to mix both ways? I had thought the timing chain issue would be more of water getting into the oil? Or is there possibly something else?

Pull the valve cover. If you dont see timing chain failure, continue on and pull the head.

You know this thing has to come apart in some way. I say just dive in.

This is probably not what you want to here but I was in a similar situation with similar mileage about 5 years ago when I got the exact same symptoms and it ended up being a head gasket failure and a warped head.

I ended up finding a reputable engine builder in my area (this is easier said than done) and purchased a rebuilt longblock for about $800. With some help from a couple buddies, I went ahead and swapped the engine, clutch and a couple other components. It was a weekends worth of work definitely made easier by my friend's engine hoist and two post lift. The overall cost was not too dissimilar from replacing the head. I ended up putting about $2000 into it including a few performance indulgences.

It has run like a top since (knock on wood) including a few years as a daily. To me it was worth it because the body was super clean and rust free and I knew I wanted to keep it for a while. Not everyone is lucky enough to have experienced mechanic buddies with nice facilities to help you out but my point is with that kind of mileage it might be worth a full rebuild or swap if the rest of the truck is nice enough. You are talking about a pretty high cost repair either way.

Ok I took your advice and dove in. Bit stressed but pulled the valve cover and I could clearly see the driver side chain guide is gone. I can also see that the chain has been wearing quite a bit on the side of the timing chain cover. I'm not sure how to tell from here if that is the water/oil problem but I'm hopeful it is. So I have now:
- removed valve cover
- drained all coolant/oil
- removed skid plate
- removed radiator
- removed fan and belts

Next step (according to some directions I found) is to remove distributer and then I think get to the timing cover itself.

I am hoping that once I get into the timing cover I will be able to confirm whether it is the culprit? If it is then I suppose I will go ahead and order a timing chain kit and new timing cover. Would love to get that osk brand but it is tougher for me to get at a reasonable price given I'm in canada. Have seen some kits on Amazon but not sure if they are any good or not - don't like putting poor quality stuff on.