This is the second one I've blown on my '94 22re. I just confirmed it by doing the chemical test (exhaust gas in cooling system).

I did a compression test (cold):

1: 140
2: 140
3: 145
4: 175

I have judiciously set the valves and made sure the head bolts (AARP) are were tight after I replaced the head and gasket 2 years and 20,000 miles ago.

When I start it up the engine runs real rough like it is rich; then after a bit it smooths out and runs normal. I can hear what sounds like a rod knocking when I first start it up and its running rough, but after the engine smooths out the knocking goes away.


The million dollar question is what caused this? The first time that I noticed something was wrong was when I was towing the trailer down the highway. When I came to a red light the temp gauge started going up. That happened a few times, but it seemed to always stay in the normal range when moving at a decent speed.

I also noticed when I got home that first day after it blew, that the coolant was boiling (or at least it sounded/seemed like it). However, the temp gauge showed that it was not too hot. So, I thought that maybe the radiator cap needed replacing. I replaced it, and I haven't heard that boiling sound since even when the temp gauge shows that things are getting hotter than normal.

Also, the engine is losing coolant, but it does not appear to be leaking out or being blown out through the reservoir. The cooling system is definitely being pressurized by exhaust gases, but not as badly as the last time the HG blew (two years ago).

Cooling fan:

Yesterday when I got home the temperature gauge was getting up there again, so as soon as I got home I checked to make sure the cooling fan was working. It wasn't. I suppose it needs some of the liquid stuff in the fan clutch that seems to leak out over time. I am running a 3-core radiator that is still rather new. I also have a dual valve thermostat from the dealer.

So, I'm not sure if the HG blew which put air into the cooling system which overheated the engine OR the engine overheated due to either (or both) a bad radiator cap or a faulty cooling fan clutch.

Bottom line is that I'm at a crossroads whether or not I should slap another HG in it and see if it will go another 20,000 miles, or if I should get a replacement. The bottom end is untouched, but the head is a newer EB head with O/S valves.