98 rodeo coolant leaking

I have a 98 isuzu rodeo 3.2 liter that I cannot figure out where I have coolant loss. I have replaced the thermostat, radiator cap, the two o-rings underneath the manifold, flushed the radiator, water pump and still losing coolant. Oh yeah, and the fan clutch. There are no external leaks that I can now see and there is no coolant in oil. The passenger side floor is not wet and I cant smell coolant inside the car so does that mean I can rule out the heater core? Can anyone please please help me cause im tired of buying coolant every other week. Thanks

Heater Core?

maybe the Rad is plugged and is pushing it out the overflow?

have you tried a new rad cap yet?

Your truck's getting up there on age, just like mine. I've had to replace tons of little coolant hoses in the last 2yrs due to rotting out, so take a GOOD look at your heater core hoses, oil cooler hose, cylinder head to cylinder head hose, there are a ton of little hoses on this engine that can leak coolant.

Also, if your radiator is original, along with your cap, these could be culprits too.

Since its a '98, also pull the coil packs on top of the plugs and see if there is any coolant in the plug wells.

hello and thanks for your reply. Now if there is coolant in the coil packs would that mean a blown head gasket and shouldnt I see the milky oil at oil changes? Thanks

No, you won't always see milky oil at oil changes.

Reason for checking your spark plug tubes is the '98 model years are known for cylinder cracking issues due to a defect in the block design of the 98-99 model years.

Its actually the heads that crack, not the block. Either way is expensive news but heads are cheaper then a block at least. Makes me nervous since mine was actually built in '98, beginning of '99 model year.

So is there anyway I would know for sure that the problem is the heads besides coolant in the coil packs?

Thinking about using some of that liquid sealer...would anyone advise me to doing this and if so what kind should I use?

If you plan on keeping the truck then I would find the leak. You never know what will happen with the quick fix sealer. You can rent a cooling system pressure tester from Autozone to try and find the leak. Get a bright light and get under the truck. If you're not losing it through the exhaust or cracked head you might be losing through the overflow.

Have you crawled under the truck to inspect for any coolant? If you can't find a leak, it has to be going out the tailpipe.

If you find any coolant in the plug wells, check out THIS POST (http://forum.planetisuzoo.com/viewtopic.php?t=25929) starting on page 2. If it turns out to be a cracked head you can PM Jerry (JLEMOND), he has new and used heads for sale. Always much better prices then going through other channels and he's a great guy.

I agree that if you dont see a leak its going out the tail pipe. Most likely a blown head gasket or bad head in that case.

Didnt find any fluid in the coil packs... so does that mean no cracked head hopefully? Gonna get under the truck today and do a complete check for leak. Oh failed to mentioned that had a pressure test done on the system and it was holding pressure.

A gallon every other week?

Im thinking its more than that...I have to drive 10minutes to and from work every day. If I fill the reservoir up its empty in about two days.

Maybe there is a crack in the reservoir?

it is pretty easy to pull out and check.

Im thinking its more than that...I have to drive 10minutes to and from work every day. If I fill the reservoir up its empty in about two days.


Hard to believe you're losing that much and not seeing it somewhere.

If you're losing THAT much, I'd say the engine is consuming it, even if the oil is clean.

Unless you do have a bad radiator, but even then, you should be able to see *something* green on the frame underneith.

Same thing occured on my late Toyota, coolant kept running away, never could find it anywhere obvious, oil was clean too....til we opened up the engine cause it refused to finally start. Whole entire bottom-end was swimming :banghead:

still havent found the leak to this day....no coolant in coil packs so im guessing a blown head gasket maybe..can anyone think of anything else before i take it to the ol dealership for a high price diagnostic?

If you aren't seeing any leaks then the engine must be consuming it.

Are you in a place where steam comes out the tailpipe every morning?

Try a pressure test when the engine is cold. Most likely you have a pinhole or tiny crack in the head near the exhaust valve and when the engine is warming up it's burning off the coolant and pushing it out the tailpipe. Once operating temperature is reached thermal expansion causes the crack or hole to close and no more leak (which may be why the pressure test passes). The head near the exhaust valve runs a bit more hot natually due to the exhaust passing through the port.

A crack in the head would keep your oil clean (whereas if the head gasket blows it typically blows between the combustion chamber and the oil/coolant galleys which is why you get milky oil).

Any bubbles in the radiator when the engine is cold and you start it up?

I still think I would dump in some stop leak in the rad to see if it fixed it.

when i top the radiator off with the engine cold there are bubbles that pop up and the fluid goes down but I thought that was just the coolant settling...then I add more coolant

Have you used some and it worked without messing any other components up...I havent heard of anyone using that stuff and it worked...

Bubbles in the coolant at the neck of the radiator = compression leak into the cooling system.

For what it's worth the leak sealers claim to work on internal components but I have never had it work. Do you want to take the risk of thinking the problem is patched and then have the plug blow loose leaving you stranded?

Sounds like you have a cracked head. Being that you have two heads I would run a compression test and check the spark plugs. Chances are one of the cylinders will come up lower and/or one of the plugs might be discolored compared to the others.

okay guys help me out here...I had a friend at work pressurize my cooling system. With the oil cap on the system passed the pressure test. With the cap off the pressure slowly began to fall. He said that it wasnt a crack head or blown head gasket cause if were either of the two the pressure would have fell regardless if the oil cap was off or not. He diagnosis was a leaking intake manifold gasket. Something about water jackets running thru the manifold which i didnt think it did. Help

Leaking intake manifold gasket is VERY common on the 2nd generation Rodeo's...so it's a big possibility.

A leaking intake manifold gasket won't send bubbles streaming into the cooling system.

If you fill up the coolant and start the engine when cold does the overflow reservoir's level rise? Does your exhaust have a sweet smell to it and does the steam linger? Normal exhaust will dissipate quickly when the weather is cold; burning ethylene glycol produces white dense steam that is rather like fog. A spark plug with whitish or brownish deposits on it could indicate the bad cylinder head.

Does anybody know where i can find a diagram of a 98 isuzu rodeo DOHC to find freeze plugs. And also, are they even possible to change out if I locate them?

Freeze plugs are on each side of the block near the engine mounts.

If you are losing coolant externally on the engine you'd see puddles and leaks unless the leak were so tiny it evaporated as soon as the engine started to warm up. I have had one car in my life with a single freeze plug that leaked and it was blatantly obvious that it was leaking.

I had a friend at work pressurize my cooling system. With the oil cap on the system passed the pressure test. With the cap off the pressure slowly began to fall. He said that it wasnt a crack head or blown head gasket cause if were either of the two the pressure would have fell regardless if the oil cap was off or not. He diagnosis was a leaking intake manifold gasket. Something about water jackets running thru the manifold which i didnt think it did. Help

This makes no sense at all.

The cooling circuit (obviously) has no connection with the lube circuit, unless you have a fault. Regardless of that, I doubt the lube circuit is air-tight enough to pass any kind of pressure test. The inlet manifold has nothing to do with either circuit.

If you have no external leaks, and no sign of coolant in the oil, then the coolant must be leaking into a combustion chamber via a faulty head gasket.

'99.

You can still have a bad head gasket, cracked head, or cracked block and still pass a pressure test. You can have a cracked head but still clean oil. You can have a bad head gasket but still clean oil.

If you are consuming that much coolant with no apparent leaks and have passed the pressure test, then I would check out a cracked head (probably near an exhuast valve because they run hotter and the temperature variation tends to make more cracks around the exhaust valve guide to the cooling system). You would need to do this when the engine is completely cold (preferably sitting overnight). Cracks can 'heal' once the engine has warmed up and this will cause a pressure test to appear to be OK. When the engine cools the crack reopens and you start sucking in coolant and/or leaking lots of exhaust into the cooling system.

This is what happened on my past Isuzu, the engine was consuming coolant, there was no bad head gasket, and, it only happened when the engine was cold. Once warmed up I could drive hundreds of miles with no coolant loss. Upon disassembly and inspection there was a crack that extended from the exhaust valve seat, through the guide, and to the spark plug hole. It closed up when the engine warmed up and opened back up when it cooled off completely.

In my case the very white steamy exhaust at startup was a clue, but, again the exhaust was clean when the engine warmed up. If I drove the truck, parked it, then came back 30 minutes later no steamy exhaust, just like normal.

Okay pretty much given up on coolant loss...Gotta be a blown head gasket or cracked...Can anyone tell me what might be the problem with idling real rough while in drive and on the brakes? If I shift to neutral or park the rough idle goes away

leaking intake manifold gasket, or fowled plugs (from burning anti-freeze)

Okay...i need some help on the things i need to purchase. Im gonna go ahead and pull my heads and have them surfaced and reworked. Is there anything special I need to do or know when pulling the heads as far as getting them off. Also, what are the parts I need on hand besides the head gaskets when going back together. I have gotten pretty good at working this engine,,even down to setting the timing. So please everyone could you give me some good imput....thanks a bunch

can anyone give me some pointers...anyone?

can anyone help me out on the procedure for pulling heads off 98 dohc v6.

Hey duke, good grief you've been at this the past 6 months! dang.

buy the auto manual thingy. it tells you exactly how to replace the head. i've got one and its a nice handy thing to have.

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MY PROBLEM: 98 rodeo keeps blowing up the radiator. I've gone through 3 radiators that have literally blown apart. It's getting exhaust into the cooling system i believe.

I'm not leaking or using cooling at all. level stays the same. Does the radiator cap also let out air pressure too? I'm on my 3rd radiator cap and still the radiator builds up so much pressure that it expands and springs a leak.

STORY ON CAR: radiator leaked coolent into engine. engine overheated and head gasket was blown. replaced head gasket but not head. Ever since then it has evidently leaked exhaust into the cooling system but not coolent into engine.

Any ideas on how to fix??

I just look under the oil cap of my 98 isuzu rodeo and found a milky build up under it....So im pretty sure this either means a blown head gasket or cracked head...Im going to go ahead and pull the heads on this car and replace the gaskets and see if there is crack in the either one of the heads...But I need some advice if there is a crack in one of the heads what other year model heads would fit this car. I have heard that the 98 had a bad mold and heads were cracking like crazy..I wouldnt want to put a head on that would eventually down the road crack..Can anyone out there give me some advice

It has turned cold there, right? If you take short trips and don't get up to temp for extended periods, you don't burn off the water in the crankcase. It is normal for some milky substance to form on the oil cap when it is cooler if you don't take long trips.

Okay thanks but your post puts me back to square one...the coolant is going somewhere...truck still runs goods no smoke no misfires but have to add coolant every week..this has been going on for over a year now...

now im getting a misfire in #3..please can someone give me some advice here

Have you done a leak down test or compression test on the cylinders?

I think the idle problem, coolant loss and now misfire on #3 would suggest either a cracked head or intake manifold gasket. IMG failure is really common on these things.

I would also do a search on http://www.planetisuzoo.com/

you should get a manual even from your local library it will prove useful. or all data online you can get it for your vehicle its only like 15. bucks a year

i replaced the img when I replaced the thermostat and the two orings on the water pipe...so are there water jackets running up thru the intake manifold the reason why i would be losing fluid if it was bad? Is there a chance that i could have install it wrong to where it could leak? I have been driving this car like this for over two years now and I really just dont have the symptoms of a head gasket or crack head..A guy at my job told me it was probably the IMG but I didnt tell him I just replaced it..

Its getting cold here in Oklahoma but I just went and check under my oil cap and there is that milky oil under the oil cap and I can see the milky residue on the head under the oil cap. But here is the funny thing, well to me anyway, the oil down in the pan is fine. What could be the cause of that? Please guys help me out..am i looking at a leaky IMG..