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    JeepGirl247's Avatar
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    What are the signs of a bad head gasket/cracked block?

    Hi everyone.

    I have a 1988 XJ with an automatic tranny, inline 6-cylinder 4.0 engine - both are the originals.

    What exactly are the signs of a blown head gasket/head gasket that is on the verge of going bad? Plus, how can you tell the difference between a blown head gasket and a cracked block? Please be as specific as possible. The more details, the better...seriously...I appreciate that!

    Thanks in advance!

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    SteelHeadz's Avatar
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    Re: What are the signs of a bad head gasket/cracked block?

    Water mixed in with oil, coolant escaping out of the exaust usually accompanied with white smoke and the smell of anti-freeze,coolant leak on the outside between the cylinder head and engine block, a cylinder or multiple misfire. All of which would cause the engine to run hotter than usual or cause an engine to overheat. As far as "in the verge of going bad", there really is no indication except for a visual leak like oil or coolant from the edge of the headgasket. I might have missed something.
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    Re: What are the signs of a bad head gasket/cracked block?

    and why would you ask this. just woundering. is someone trying to talk you out of your jeep

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    Re: What are the signs of a bad head gasket/cracked block?

    SteelHeadz - thank you for the answers
    tp=n=yj - nobody is trying to talk me out of my Jeep - I'd never ever EVER part with it

    Here is what is going on...for the first time last winter (PA is famous for experiencing the extreme climate changes of all four seasons), there was a "coffee creamer" discoloration on the oil dipstick, plus some moisture dripping from the tailpipe. The exhaust smoke was normal, though, and the Jeep ran like usual, so I figured it was condensation - because when the weather warmed up permanently, the oil was it's normal color again.

    Fast forward to this year - the oil got changed and then the weather started to get cooler. I check the oil level every singe time I take the Jeep anywhere because it has a terrible oil leak (rear main seal, pvc system, oil in the air filter box, about 75% of the area under the hood is oil drenced from the many years of this pesky leak) - so I notice any discoloration on the dipstick right away.

    Well, two months ago, a coolant hose coming from the reservoir totally exploded while I was driving and a ton of coolant went all over everything and made a trail on the highway to where I pulled off the road and called the mechanic. He did a sort of bypass quick fix on the spot (basically put a metal pipe in between the two pieces of the ruptured hose and clamped it) That was when the mechanic told me that it was caught in time and didn't hurt anything.

    Fast forward to a couple weeks ago when I started noticing the "coffee creamer" on the oil dipstick again for the first time since the ruptured coolant hose. I'm much more concerned this winter noticing it because of that and also because the Jeep just hasn't been the same. It has the moisture from the tailpipe and there has been a lot of white smoke from the tailpipe. The engine compartment reeks of burnt oil and another odd smell - which I am afraid may be coolant. The coolant level in the reservoir is fine and there is no oil visibly mixed in with the coolant there. The Jeep just also hasn't had as much power as it usually does - it's uphill acceleration isn't as good and twice last week it actually jerked back and forth to struggle to upshift to get up a hill. Plus, the heater/vent will turn off and shoot out the defroster on the top of the dash when I go up hills - not sure if that means anything specifically.

    So, that is what I've been dealing with and it has me rather scared. Is it okay to continue to drive the Jeep short distances? What would be a good plan of action for me to take to solve this?

    Thanks again,
    JeepGirl247

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    Re: What are the signs of a bad head gasket/cracked block?

    I can just about guarantee that at a minimum the head gasket is blown with the coffee colored oil. I've experienced it twice on a Ford and Mercury but not on a Jeep. Not sure about the cracked block but you'll probably find out after the head gasket replacement. If I had to bet I would bet against the cracked block but a cracked head is still a distinct possibility. Hopefully, PA is still a reasonable area for repairs because MD shops think everybody is a doctor earning $250K a year.
    Good Luck

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    Re: What are the signs of a bad head gasket/cracked block?

    If the mocha colored oil is only found on the upper portion of the dipstick, i would consider that normal due to weather intrusion on the top of the tube. I've seen the same results on other Chrysler models. However, IF the mocha colored oil is in the oil pan, that would indicate a coolant mixed in with the oil. The smell of burnt oil could account for the oil leak you mentioned on the rear main seal thats splashing on the exaust and giving you that smell. Struglling uphill on a shift issue could indicate a transmission service is in order. When was the last time you had it serviced?. Last but not the least, the vent switching from panel to defrost on a high RPM or hard acceleration would indicate a lack of vacuum supply to the HVAC actuators, meaning , a possible vacuum leak. Check all your vac. lines for small cracks or partially disconnected from the fitting. Back to the cooling system. If you have doubts on the head gaskets integrity , there is a tool and chemical that you can purchase from a local parts house. It's a "Block tester" that uses a blue chemical . The tool is installed on the radiator filler neck and a vac. supply. A certain amount of the blue chemical is poured into the glass tube of the tool, this chemical will turn yellow if the presence of exaust gasses is in the cooling system. Follow the instructions with the tool very carefully to get an accurate result if you decide to do this.
    Last edited by SteelHeadz; 02-03-2010 at 06:50 AM.
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    Re: What are the signs of a bad head gasket/cracked block?

    Yep i'd have to say it's prolly a blown head gasket if the mocha colored oil is all the way down to your oil pan, my brother used to have an s10, he blew the head gasket on it, water all in his oil, looked like mocha coffee. Better a blown head gasket then a cracked head though.
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    Re: What are the signs of a bad head gasket/cracked block?

    I appreciate everyone's responses to this issue. I prefer to have some knowledge about what is going on before I would take it to a shop.

    I added some coolant today and the coolant in the reservoir has no signs of oil mixed in it there. The oil dipstick DID have some white discoloration about 5 inches above the "full" marker level on the upper part of it where no oil was - and it also had the discoloration mixed in with the oil on the very bottom tip of the dipstick and when I turned the dipstick over, it was discolored in the middle of the dipstick (around the "add" marker area). I looked underneath and did not see any signs of coolant leaking anywhere, just the oil. I didn't see any visible coolant leaks in the engine area - however, I didn't start it up because I was checking the fluid levels cold. I will look and listen when I start it up tomorrow.

    The automatic transmission is the original also and has been slipping out of gear and occassionally not upshifting from first to second gear. Both of these things happen only during the first few miles of a trip and only in the cold weather. It usually doesn't act up too bad during the warmer weather - I will also add that sometimes it doesnt even act up at all during a trip on a cold day. Anyhow, it was last serviced with a professional fluid flush and filter change a few thousand miles ago. It corrected the slipping problem for about 300 miles, but then it's been acting up ever since.

    Here are a few more questions that I have about the head gasket - does anyone recommend getting a shop/dealership to perform a compression test? And, if it is the head gasket that is blown - is it better to invest in a brand new engine or just replace the head gasket? Also, I know that prices vary from state to state and shop to shop, but what is a general price estimate at what a repair like this could cost - a head gasket repair vs. a brand new engine? And, one more question - does it hurt it worse to drive it while it is like this?

    Thanks so much.

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    Re: What are the signs of a bad head gasket/cracked block?

    It's still unclear to me if the engine oil itself is contaminated from your description on what you've seen on the dipstick. Is it possible for you to take a pic. and post it?. As for the compression test, you should be able to do that yourself if you can borrow a friends compression test gauge. However, cost wise, if you decide to buy a set of comp.test gauge from your local parts store and only intend to use it once, and if the cost to get the test done by an automotive shop is just as much, i would say that your probbably better off getting the test done by a professional. That's my opinion on that. Moving on engine replacement or replace the head gasket. That depends on your budget. It's always a better move to replace an engine with high mileage and with a possible head gasket or crack in the cyl. head with a new one, and if so, make it a long block. Since your also having issues with the transmission, that adds up to the problem solving of fixing it all together. So at this point, IF i was in your shoes, i would consider the cost of a long block, and the cost of the transmission to be rebuilt or repaired. The question is, is it worth spending all that Vs. selling it and just buy another jeep that doesn't have all the headaches?, since you've already made up your mind that you never want to part with it, i think a new fresh engine and a remanufactured transmission from a reputable source would be my move. Then you would have a peace of mind with the added security of a warranty on the engine and transmission. If you decide to get the head gasket replaced, make sure you take the cylinder head to a reputable machine shop to get it checked for cracks and have it resurfaced. Check the cylinder block and cylinder walls for minute cracks, gouging, scouring and flatness on the top. I hope this helps you a bit, i really would like to see a pic of the oil on the dipstick and if possible, the oil in the oil filler on the valve cover.
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    Re: What are the signs of a bad head gasket/cracked block?

    Thank you, SteelHeadz. I will get a few pictures up of what you requested. In the meantime, though, I had the Jeep out and it was really having a lot of white smoke from the tailpipe. Plus, I went up a gradual incline for a few miles and it barely had any "get up and go". I decided to experiment and slowly push the gas pedal to the point where it was touching the floor and it didn't do anything, so I let off and tried it again a minute later and there was still no extra acceleration. My top speed was about 25MPH going up the hill. After the engine cooled off a good 12 hours, I checked the dipstick and the oil was rather clean looking, except for a little bit of milkshake towards the middle of the back side of the dipstick (around the "add" level marker). However, my concern is that if I would go check it now after it setting for a couple days that the oil would be settled enough and that there would be the milkshake at the bottom tip of the dipstick - does that make sense?
    So, I'll get those pics taken and upload them soon - hopefully that will help.
    Thanks again.

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    Re: What are the signs of a bad head gasket/cracked block?

    is it hard to start? sometimes the gasket doesn't leak to oil or water, sometimes it leaks only to another cylinder. take your oil filler cap off and see if you have lots of pressure when its running, sometimes that can be a sign also but this one depends on if you have lots of blow by too. sometimes you will get an odd colored milky build up on the underside of the oil filler cap and if you pull your spark plugs, one at a time, if one or two are really clean looking then those are usually the ones with the headgasket leak since the water is getting into the cylinder and adding more oxygen to the fuel/air charge causing it to burn hotter.

    since you are losing power then maybe your cat is reading that you are running lean and adjusting by dumping fuel into the engine and making it run rich? pull your oil dipstick and smell it. does it smell strongly of gasoline?

    the main way to tell is to have grey funny milky looking oil either on the dipstick or in the filler bottle and then having to add water pretty regularly. my 82 bmw needed water every other day for about 7 months so i knew the headgasket was going out. finally one hot day it went in bad traffid when we had a bomb scare at work so i got to sit on the side of the road and watch everyone else leave.
    I love my old jeep.

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    Re: What are the signs of a bad head gasket/cracked block?

    Thanks SuperJ. I haven't seen any type of discoloration around the oil filler cap into the valve cover - just on the dipstick. The oil itself is not discolored completely - it was just changed a few hundred miles ago and looks relatively light colored still. My Jeep has had a ton of blowby over the years - even before I first noticed the milkshake discoloration on the oil dipstick (which was last winter). The air filter gets completely saturated with oil and has to be replaced frequently. If I park it for just 30 minutes there will be an oil spot under it.

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    Re: What are the signs of a bad head gasket/cracked block?

    At what RPM is it running when you have the fuel pedal on the floor?. when the engine is at it's normal operating temperature and if it bog's down at 1500-2000rpm with a lack of power , this may indicate a plugged up catalytic converter. One way to tell is the exaust sounds like it's getting choked as opposed to hearing the engine rev. up to a high rpm without hesitation. The white smoke may be normal at first start in cold temperatures and should dissipate when the condensation in the exaust goes away.
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    Re: What are the signs of a bad head gasket/cracked block?

    i would say the milk shake in the winter was probably condensation in the case from the cold weather, since you ahve nothing anymore. i would def check that cat though.

    maybe you should put a catch can in-line to your crankcase breather line. it'll save you an oil filter.

    does your exhaust have a fitting in front of hte cat? if so, unbolt it and drive around to see if it makes a difference. if so, then you know the cat is done
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    Re: What are the signs of a bad head gasket/cracked block?

    If the rad isn't going down and it's not overheating, then the PCV system isn't working right to remove the water vapors from the block when running (it's worse if you do lots of short truips)
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    Re: What are the signs of a bad head gasket/cracked block?

    Thanks for the responses, everyone. I have another question about this...I read somewhere online while researching this further that if there is smoke coming from the oil dipstick tube/holder that it is a head gasket problem....does anyone know anything about that? There has been a ton of smoke coming from the valve cover cap when I take it off after it has been running a good 10 miles...does that mean anything?

    Thanks.

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    Re: What are the signs of a bad head gasket/cracked block?

    no, that could just be oil that is getting thrown around from the valves and then blown out. put your hand above the hole when you take hte cap off and see if you get lots of oil drops on your hand, if you do then you knows it just oil from the valves.

    if it is actually water vapor then i would say that you have alot of condensed moisture in that block and need to drive it for a long run to get all the water out of the interior of the block. i have never heard of smoke coming from the oil filler being a blown headgasket but that doesn't mean its not possible, i just have not heard of htat happening to anyone with a blown headgasket.

    any new symptoms? more water loss or funky colored oil on the dipstick or in the radiator?
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    Re: What are the signs of a bad head gasket/cracked block?

    As far as new symptoms go...there has been hesitation/seizing or whatever it is technically called while I am driving it with a steady speed -neither pushing the gas pedal further down or letting up on it. It has a marked power loss - granted it is nearing 200K on the original engine and it isn't as fast going uphill as it was when it was at 25K, but since the coolant hose blew I have noticed an acceleration loss. I can push the gas pedal to the floor going up a hill and it won't accelerate at all, but if I get a running start before I go up the hill, it has it's usual get up and go with some acceleration loss as the incline increases. The oil still has the whitish discoloration at the very tip/end of the dipstick and when I flip it over it is also mixed in slightly at the top.

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    Re: What are the signs of a bad head gasket/cracked block?

    I'd get a radiator pressure tester, even if I had to make my own. Pump it up to around 25 PSI let it sit for awhile and watch the pressure gage. If it goes down, it's obvious there is a leak somewhere. Don't pump too much pressure in there anything over around 30-35 PSI may pop a hole in your radiator, if you look closely you can watch the copper passages expand. I made my own tester (for my Renix), a short piece of old radiator hose, a plastic cap a couple of hose clamps and a tire valve in the plastic cap. I use a bicycle pump to pump it up, my bike pump even has a built in pressure gage. Low tech but it works LOL.

    If it isn't external, it is likely internal, either coolant leaking directly into the oil or leaking into a cylinder and passing through the ring gaps to the crankcase.
    I've pulled the spark plugs on motors with head gasket leaks and seen deposits on the plug ends that look kind of like tiny cotton balls (sometimes white, covered in a light coating of carbon, sometimes even tinted the same color as the coolant) or if the leak is really small, sometimes you get really clean shiny metal electrodes on the end of the plug (steam blows the carbon off the ends).
    If you have a moderate coolant leak into the cylinders, when you start up cold and the condensation comes out of the exhaust, hold a clean white piece of paper towel just below the exhaust and collect some of the drops, if it is tinted the same color as your coolant, it's a likely tip off.
    Lastly check the vent action on your surge tank cap (radiator cap), if it is stuck shut, it can greatly increase pressure and the amount of coolant being forced through the leaky head gasket.
    Usually when a head gasket leaks into a cylinder it will pass coolant into the cylinder and will also pass exhaust into the cooling system. The coolant often bubbles and foams at the top.
    I've drained the oil and put it into a clear plastic five gallon water jug before, let it sit for a couple of days looked to see what's at the bottom.
    Or find a piece of plastic tubing that fits down the dipstick hole (after letting the vehicle sit over night) and when it hits the bottom of the pan, suck some fluid out. I use an old wind shied washer pump.
    If the coolant level isn't going down and the oil level isn't going up, it's unlikely to be a very bad coolant leak.
    I had one bad coolant leak (head gasket on a Chev.) that actually filled a cylinder with enough coolant to bend a valve, compression went down really low. Hot exhaust gases in the cooling system ran the engine temp. gage up pretty fast (and high).
    Last edited by MudderChuck; 03-06-2010 at 05:32 PM.
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    Re: What are the signs of a bad head gasket/cracked block?

    Thank you for the helpful hints and sharing your experiences, MudderChuck. I like the idea of the white paper towel at the exhaust.

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