Kinda hard to say Rob. You might be able to warm up the engine, then(VERY CARFULLY!!) take off the radiator cap and have someone rev the engine while you watch the coolant. If you see bubbles... that's not good. If you see MORE bubbles the more you rev it....that's worse. Not saying that's the only way, or best way to check it, but it has worked for me several times.

<EDIT>I suppose you could also pressurize the cylinders with compressed air some way and watch for bubbles(like above) without starting/running the engine. I have never done it that way, but it MIGHT work. The air pressure used would need to be pretty high though. Engine still needs to be wamed up too. Small cracks seem to get bigger(and leak more) as an engine warms up.

Here's hoping you don't see bubbles. <img src="/forums/images/graemlins/cheers.gif" alt="" />

I've kinda done what you described and actually had the water level rise and flow out of the top. no bubbles that I noticed, but the level did seem to rise and not want to stay contained in the radiator without the cap on. I'll attempt to verify again.

I also haven't seen any signs of water contamination in the engine oil.

-Rob

Rob, that is normal. Bubbles are bad.

Try this. Smell it. Hot, cold, running, off, it should not matter. If it smells like fuel or exhaust, then there might be a problem.

Michael

Take a nasty shoprag and light it on fire let it burn for a second,then put it out.If your radiator fluid smells like that nasty burnt rag then you might verywell have a blown head gasket/cracked head..........momma ain't been hotroding her Trooper has she <img src="/forums/images/graemlins/notooth.gif" alt="" />.

Anyways do a compression test and leak down test.Not sure of the numbers but try it for cylinder to cylinder comparison.

Compression test

remove fuel pump fuse( and run engine out of gas)
Remove all plugs
prop open throttle plate
screw gage into plughole
turn engine over at least 2 full turns and record highest reading.
repeat----this will tell you the Lbs of pressure per cylinder they should be w/i 10%
If you have a low cylinder put about a teaspoon of oil into the cylinder ( a syrenge works best covers all parts of rings)
retest that side
if numbers improve than rings are leaking
if not then either valves are leaking or major head problems

Which brings up a leakdown test
very similar to compression test but you need a leakdown tester.

Remove fuse and run engine dry
prop open throttle plate
remove plugs
ensure valves are closed for each cylinder being checked
insert tester gage
apply 90lbs or so of pressure
remove air source
see how long air takes to leak out
in a perfect world none will leak out.

record all cylinders if 1 is low then repeat oil step as above to see if this "seals" the rings,if one cylinder is alot different than the others there is something wrong in the head area.

This will also allow bubbles to escape thru the coolant.

If the thermostate is closed bubbles will not appear so take out the thermostate before applying air to the engine.

This air into the cylinders will actually hold a valve closed to repair valve seals/springs........only keep the air applied so the valve doesn't drop down.

Disclaimer---check pressure req. and readings in the service manual before doing this <img src="/forums/images/graemlins/smile.gif" alt="" />

Goodluck

This is an important question, if it'll sit and idle and seem fine, but driving makes things worse this might point to blockage in the radiator. The "Garden hose flush" is good as a preventative measure but won't break up scale wedged in cores. On a warm engine the core temp tells the tale, much cooler at the bottom indicates a clog. Normally the coolant is cooler at the bottom of the rad, but it's still well above 130* before re-entering the engine. If your '89 has A/C and the shroud/clutch fan, access to the rad core is limited but you could shut off the engine and QUICKLY feel around the core by hand for cool areas.
How is the resistance of the fan's clutch when warm? It's normal for coolant to enter the expansion tank whilst engine reaches normal op temp, and to be slurped back in as it cools. Half the rad's contents sounds extreme, how much did you actually add?
Another simple test for combustion leakage is to fill the radiator completely up to the overflow tube (this can take a while as coolant will settle, especially if the bleeder is used). With coolant level stabilized, remove harness wire from ign coil and crank engine while observing open rad filler for bubbles (or giesers!). Should have a lab assistant in a wetsuit and goggles for that test.
Another test for radiator flow; Remove both upper and lower hoses and allow rad to drain completely. Next "fill" the radiator with briskly running water. If the flow of water is greater exiting the upper hose connection you've got clogging in the core. From a full force garden hose almost ALL water should exit lower hose connection.
There's more, but try these simple (and free) tests first.

Granted that it was on a V6, but have heard a rumor of someone who inadvertently switched the lines going to the expansion tank when he first got his red Trooper, but before he had put on the ARB bullbar, etc. Since that unnamed person had just purchased the vehicle used from a dealership, he took it back to the dealer. The dealer had the vehicle for a full day each of two times and was unable to determine the cause of the problems that sound identical to your symptoms.

The dealer never found the cause of the problem but the owner eventually did. That discovery has led to steadily downward spiral in the owners character, epitomized by his current role as a moderator, but he shall remain unnamed.

This sounds like a job for Mr. Infra-red Hand-held Thermometer!

Now _that_ is something for Auto Mechanics 101 if I ever heard it ! <img src="/forums/images/graemlins/lol.gif" alt="" /> <img src="/forums/images/graemlins/lol.gif" alt="" /> <img src="/forums/images/graemlins/lol.gif" alt="" /> <img src="/forums/images/graemlins/lol.gif" alt="" /> <img src="/forums/images/graemlins/lol.gif" alt="" /> <img src="/forums/images/graemlins/lol.gif" alt="" /> <img src="/forums/images/graemlins/smile.gif" alt="" />

<img src="/forums/images/graemlins/cheers.gif" alt="" />

I have had about 8 or so engines in my life/shop do this. 7 had cracked heads, cracked blocks, or blown head gaskets. 1 had an upside down thermostat(real fountain from the radiator there!!!!)

I vote, almost with my life, cracked head or blown head gasket. Sorry, that isn't what you wanted to hear.

Spencer

I forgot to mention: To test, pressurize each cylinder with an air gun. Obviously, make sure the cylinder is at top dead center first so that the valves are closed. Then nothing fancy - Just wrap the air gun in a rag and press hard against each a spark plug hole and give it a couple of quick puffs. You'll hear or see bubbles when you get to the cylinder near/under the blown gasket or head crack.

A blown gaset or head crack may also generate a slight leak into the combustion chamber that you won't be able to notice. If that is the case, pulling the spark plug may reveal the leak as coolant/moisture would be on one or more plugs.

Spencer