diagnosing a headgasket failure

[joegri]

i wanted to make sure that i have a head gasket failure this is what i,ve done. i searched the entire block and head gskt nothing there. i pressure tested the system to 18 lbs slight leak in a heater hose fixed that. there is no coolant in the oil. my nose doesnt work that good these days so i cant smell any coolant from the exhaust. no white smoke from exhaust i pulled the plugs today 1 was kinda black and the rest were white? i add a cup or so of coolant a day, so where is it going??? and lastly a head gskt kit who do you buy from. i did this job 4 years ago on a different van using a felpro kit that the machine shop sold me it worked fine. but i keep reading use only toyota. my goal is to try n nurse it through the winter cuz i dont have a garage and i need the van for my heating service. any thoughts? thanx in advance joe g

[timsrv]

To save some time, here's a copy/paste from another thread on this forum:

Head gaskets can blow in different ways. It all depends on what part of the gasket or mating surface is damaged. There are several ports where oil and coolant travel between the head and the block. Then theres the cylinders and they contain high pressure combustion gases. The head gasket's job is to seal all these areas and keep them separated from each other. If the gasket and/or the mating surfaces become damaged between an oil and a coolant port, then these two fluids can mix creating a milky brown foam in the oil pan. Oil can also enter your cooling system and should be evident when you look into the radiator fill port (oil will float on top of the coolant).

Sometimes the leak can occur between a cylinder and a coolant port. When this happens combustion gases can pass into the cooling system and depending on the severity of the leak, the combustion pressure can force coolant out of the cooling system overflow (this leads to overheating). Sometimes coolant leaks into a cylinder and is expelled through the exhaust in the form of steam. In severe cases coolant can leak into a cylinder after shut-down and hydro-lock the engine.

Sometimes the gasket can blow between cylinders. When that happens the end result is 2 cylinders next to each other that have low or non-existent compression. If the van runs at all it will have severe performance problems and/or exhibit a very bad miss.

Sometimes the gasket can blow allowing coolant to leak externally. This type of blown gasket simply causes your van to lose coolant and depending on the severity it can still be used like this for extended periods (assuming you keep the coolant levels topped off). I have been experiencing this type of head gasket failure (for over a year now) but the severity of the breach isn't terrible, so I continue to top off the coolant every couple of weeks. I also get to look at a small puddle of coolant on my garage floor every morning when I leave for work (I need to fix this one of these days).

So, to sum things up, your head gasket can fail in any one of these ways or a combination of 2 or more ways at the same time. Based on the fact you are getting coolant in your oil I'd say your problem is the 1st one type outlined. Of course it could also be a crack in your head or block, but by far having the head gasket fail is most common.

Depending on how much you drive, 1 cup per week can be a very small leak and as you know small leaks can be hard to find. On these vans there are several places that leaks can occur undetected. To find a leak of this size you may need to invest in some tools and spend some time troubleshooting. Coolant leaks are often intermittent (some leaks occur only when cold, some only when hot, and some only in transition between hot & cold). Before condemning the head gasket, I would gain as much access as possible by putting on jack stands and removing the passenger seat / engine access panels. When the van is stone cold, pressurize the system to around 15psi using a testing device (see picture below).


Note: This type of hand pump/testing device is easy to find for purchase but may also be available for renting at a larger auto parts store. If you're thinking of buying, even Amazon has these http://www.amazon.com/Stant-12270-Co...5318080&sr=8-1.

Let the van sit for about 15 minutes while monitoring pressure then begin a careful inspection of the radiator, heater core areas, and any possible place that coolant could be externally leaking. If the van holds pressure for 1/2 hr or more with no detectable leaks, then start the engine and continue your inspection as it's warming up. WARNING: Be very careful of moving parts (like the fan/belts/pulleys) and hot exhaust!. Keep in mind that while the pressure pump is on the van will not automatically vent pressure, so you will need to monitor and manually adjust pressure during the test. All of these testers have a manual pressure relief valve on them so use it as necessary.

I'm guessing you will find it before the van reaches normal operating temperature, but if nothing leaks during this time I might start to suspect a head gasket problem. Note: While checking for leaks be sure to monitor the small 8mm heater hoses by the throttle body and the infamous "hoses of death" outlined in THIS THREAD. Also use a flash-light and a mirror to check the side of the block under the exhaust manifold (see example of leak below).


Assuming you still haven't found it, and you are now convinced it's just got to be a head gasket, it's time to do an HC test of your cooling system. For this you will need to take the van into a mechanic with the proper test equipment or you can buy a "do it yourself" test kit at Napa. Napa sells a chemical tester for about $40 and you can test for this yourself. This kit includes a test tube like device and a bottle of blue chemical. You put the chemical in the test tube and hold it over the top of your filler neck while the engine is running. Then you take a bulb (also included in the kit) and use it to suck air/steam from the filler neck. If combustion gasses are present the chemical will change to yellow. If it fails that test, then you know it's the head gasket

A couple of tips worth noting. A careful visual inspection can often reveal the source of the leak even when it's not leaking. Keep your eyes peeled for green/greenish blue residue and crystals on or around anything that could be leaking. Your water pump is mounted to the timing cover and coolant can leak from behind the timing cover..........so check there too. Also, our overflow bottles have a level sensor in the bottom and these themselves can leak..........so check around this area too. The rear heater core is right behind the passenger side front tire, so be sure to check that area as well. With the engine off, grab your radiator fan and try to wiggle it back & forth. Sometimes the water pump will wear out and coolant will leak out the shaft. If the shaft is loose (wiggles side to side), then that's a dead give-away. There is a "weep hole" in the bottom front of the water pump housing and sometimes the coolant can drip out here and be slung about by the fan pulley. With the heat of the engine compartment this can cause the coolant to evaporate before it drips to the ground. Happy hunting and keep us posted on what you find. Tim

PS: If you end up diagnosing a failed head gasket, Here's a post that should help you make that repair: http://www.toyotavantech.com/forum/s...=3009#post3009

[joegri]

wow tim that was an excelent read !! i think i,m gonna go with the chemical test. i spoke with a wrench friend and he has that testing kit. i spect i,ll start squirelling all the lil things that i,ll need and go ahead and do this job. if i grovel good enough i can prolly get some garage space in 1 of 3 places. thanx so much for the informative reply. till then i,m just gonna quench the beast and wish for the best!! thanx again

[timsrv]

No problem Joe. The "cold to hot" leak test can also be done without the pressure tester. The tester simply increases your chances of finding the leak.

As for your gasket question, I'm sure there are other gaskets (besides Toyota) that are good too. The problem is not knowing which ones they are. From what I understand there are some out there that don't even have all the passage holes in the correct spots. Considering the time and expense of doing this job I'd consider it too big of a risk to purchase an aftermarket kit. Toyota sells a "valve grind kit" Part #04112-73035 for about $95 (if you purchase from a discount internet site like www.1stToyotaParts.com). That kit includes the head gasket and every other gasket/seal you will need for the job (so it really isn't that expensive).

PS: I re-read your original post and see it leaks about a cup per day (not per week). That's even better from a troubleshooting perspective (makes it easier to find). Good luck. Tim

[llamavan]

+1 to Tim's suggestions. Tracking a coolant leak is a real pain, but a LOT cheaper and easier than a head job or an engine swap ... and soooo much better than doing one or both of those jobs only to have it still leak when you're done.

1 cup per day sounds like a lot to be losing without also seeing other performance symptoms ... unless it really is just a leak. Your single black plug may be oil-fouled; leaking spark plug o-rings are not uncommon (usually cylinder 1).

If the block and engine bay aren't squeaky clean, start with that first. Coolant on top of oil looks like oil, for instance. Coolant on top of semi-greasy dust looks like oil too. (Go ahead, ask me how I know ...)

If you want to give it a go without pressurizing, run the van (try to stay out of the mud and puddles) and then look around with an LED flashlight. At least some green coolants will show up very strongly in the LED light (to increase the contrast, don't use other light in the engine bay). I have located more than one tiny pinhole in a coolant hose that way.

Also consider that one or more of the coolant PIPES may be leaking. The one alongside the drivers' side of the engine block is a common culprit, although hard to see from above.

If you are still seeing coolant sprayed all over by the fan, think "water pump" and "radiator" as well as "local" hoses.

A small breach in the hose from the filler neck to the overflow tank can keep the van from sucking coolant out of the tank the way it's supposed to, and also suck air into the system which makes it want to boil over. (Um, ask me how I learned THAT, too).

A bad radiator cap can cause coolant loss at the filler neck (again, personal experience).

If you have A/C, have you dropped the condenser and inspected all the heater hoses (and front heater valve) hiding "underneath" (actually above) it?

Lots to look at !!!

FWIW, I've driven a van with a BHG and it didn't use anywhere near 1c per day (my commute is 40-50 miles). OTOH, I am waiting for better weather to tackle a coolant pipe leak in one of spouse's vans ... and that one IS using around 1c per day. Food for thought ...

Gwen

[joegri]

hi again i dont want to bore you guys with my problem but, i think this could be a signal as to what is happening with the primer van. just for a hunch i decieded to insert this plastic bottle that tennis balls come in. it mounts nice in front of the expantion tank. so after a week or less of adding coolant to the gooseneck i find now that the expantion tank has filled up and now it is over flowing into the tennis ball tank?? hummm. this tells me that there is a problem somewhere else instead of a cracked head gasket.... i think i hope. in short the coolant is being sent back to the tank and when full it would just shoot out. i did look in trouble shooting the cooling system but didnt find what i needed to hear. so i,m counting on you guyz to set me straight on why the coolant is being forced back to the expantion tank.