• Other parts to replace while replacing Head Gasket

    Please read Diagnosing Head Gasket Failure before getting started (if it ain't broke, then don't fix it). Okay, so you've diagnosed a failed head gasket and there's no denying it. That's too bad, but your van is getting old and these things happen. This can be a great opportunity to make other necessary repairs (while you have the access). How much you do will depend on the condition of other parts, how much time you have and how much money you are willing to spend. Considering the age and the high temperatures in our engine compartments, if you want the van to be dependable you will most likely have a fair amount of extra work to do. As you know a series of judgement calls is always part of any major job. Some work will be absolutely necessary but other things can wait. Considering access issues, while you're in there you should probably do many more things............or end up kicking yourself later.

    Once you get the head off you should take it into a reputable machine shop. Once there they can check-over/rework anything that's questionable. Also, if you break/strip out any exhaust bolts/bolt holes, they can easily remove and repair/replace while they have it. They should also check for cracks, check the valves, guides, and shave the gasket surface to ensure it's flat. Some shops will want to do everything regardless if it needs it or not, so unless that's okay with you be sure and tell them only to repair and replace as necessary. If you bring it in without the rocker assy, be sure to tell them the valves are of the "non-adjustable" type so they know to remove the very minimum of material when/if they shave it. This is also helpful information for them to know when grinding valves (as they will need to grind some off the valve stems to compensate for the material they remove from the head and valve seal areas).

    To simplify your parts purchase, I would recommend purchasing a genuine Toyota Valve grind gasket kit and be sure to hand the machine shop the valve seals from that kit when you drop off the head (otherwise who knows what they'll use).

    Of course, this is all assuming you wish to have head work done by a shop. If everything looks fine when you get the head off, and assuming you can see an obvious flaw in the head gasket, then you might take a chance and just simply replace the gasket. Regardless of how far you go, gasket surface clean-up and prep is critical. Take steps to avoid introducing grit or foreign material inside your engine. After you're done scraping the mating surfaces use a strong solvent like lacquer thinner or carb cleaner to wipe these down. Before final assembly it's a good idea to use brake-clean for the final cleaning (as it won't leave any residue). If you decide to "chance it" you should take the time to check a couple of things before proceeding. You can do a poor man's valve seal inspection by turning the head upside down and filling the chambers with carb cleaner or brake clean. If there is a warped valve or one with a bad seal the cleaning liquid will leak out of the chamber. If it leaks a lot then you'll need to take the head in for repairs. If it leaks a little, then you could probably get by with lapping the valves by hand. If you decide to lap by hand you will need a valve spring removal tool. These can be rented at most of the big auto parts stores our you could purchase one for around $50 or so. If you remove the valves, be sure to keep track of where each one goes as you will want to put them back into the original holes. Removing the valves will also allow you to clean them and inspect the valve guides. You will also be able to replace the valve seals (can't be done with the springs installed). You can check the guides by trying to wiggle the valves side to side in the guides. If you find one with excessive side play then the head will need to go in for repairs. Any time a head is off it should also be checked with a straight-edge. Assuming you have one available to you, it should be laid lengthwise on each side then diagonally (both ways) on the gasket surface. Each time it's in position feeler gauges are used to determine if the head is warped. Here's a link to more detailed information on how to check out your cylinder head: http://www.toyotavantech.com/forum/e...Rebuild-part-2
    Here's a link to other head work you can do yourself: http://www.toyotavantech.com/forum/s...ngine-Overhaul (see posts #5, 7 & 12)

    One final thing to consider is head-bolts. I've always re-used the old head bolts, but I've heard of others having trouble doing so (bolts broke during final torque). Perhaps they over-torqued or just weren't smart enough to know how to even use a torque wrench, but this is a commonly debated subject. Its a subject each mechanic should consider and many choose to purchase all new head bolts. Always lube the threads and contact areas of the head bolts (under the heads) with engine oil and follow correct torque values/tightening sequences outlined in the service manual.

    While reassembling the rest of your engine you should pay attention to lots of little details. Most (if not all) rubber parts and hoses will almost certainly need to be replaced. You might be interested to know that back in the day the flat rate manual called this a 9 hr job......ah, well, not a reliable figure any more. When the van was within 5 years old that was about right, but now in it's old age and hard miles I would plan on 12 hrs minimum. I suspect you will probably be dealing with at least one broken exhaust manifold stud (the one in the very back) and it's likely the exhaust manifold will also be cracked (the back runner). Here's a good thread to help you through these issues: http://www.toyotavantech.com/forum/s...-exhaust-studs.

    Since you will also have good access to your throttle body (intake removed) now would also be a good time to clean it and replace/adjust your TPS. It's been my experience that the TPS will rarely make it past 150k miles, so unless you know history I'd consider replacing it routine maintenace: http://www.toyotavantech.com/forum/c...hrottle-Body-1. Other parts I'd highly recommend replacing are the engine thermostat & gasket (Toyota T-stat #90916-03046 Toyota Gasket #16325-63011). New water pump belt and a new radiator cap should also be considered must-do items. On these items I don't consider Toyota to have the monopoly on quality. I consider Gates Micro-V belts to exceed Toyota's quality and the Gates radiator cap rivals Toyota (beats the hell out of them for price). Gates part number for the cap is #31333. Water pump belt = Gates #25-050323. FWIW, if you go to Napa and ask for their premium quality belt you will get the Gates Micro-V. Injector connectors will also need to be carefully inspected. These connectors get hard and brittle and are likely to break upon removal. Due to the impossible to reach locations of injectors #3 & #4, if these connectors are not perfect, then replace them BEFORE putting the intake manifold back on. 88 & 89 vans use the "inverted Nippon" style connectors and these are all but impossible to find. Toyota does not sell them and it's likely salvage yard vans will also have brittle connectors. There is however a bright spot here. Several Subaru models from the late 80's to the mid 90's use this exact connector. Due to their placement on the Subaru engine these are almost always in pristine condition. Last time I needed some I went the the Pick-n-Pull and came out with a dozen. The guy at the counter charged me $0.35 each. If you can't save the conductor part of your old connector then be sure to solder and shrink tube the "new" ones onto your harness. This is not a place to take short-cuts (butt connectors simply won't do). As for the injectors themselves & other fuel system parts, here's a link to a forum discussion on the subject: http://www.toyotavantech.com/forum/s...el-Injector(s)

    Minimum part purchase required for this job is a Valve Grind Gasket Kit Toyota Part #04112-73035 (for 4y) or part #04112-73054 (for 3y). Stay away from aftermarket head gaskets! Just in case I wasn't clear, I repeat STAY AWAY FROM AFTERMARKET HEAD GASKETS!!! As for hoses and their part numbers, here's a good thread: http://www.toyotavantech.com/forum/s...op-End-Rebuild. Also, you may also wish to review the "hose of death" thread before jumping in there: http://www.toyotavantech.com/forum/s...f-death-thread.

    FYI: A few common mistakes (below):

    Mixing up push rods
    Push rods, lifters, and rocker arms are all the same when new, but as they break-in they develop unique wear patterns. Because of this, after break-in they should always stay paired with the parts they were originally mated with. Swapping push rods around or flipping them upside down will make them go through this break-in process again. Depending on how similar the wear patterns may (or may not) be, mixing these up can cause excessive wear and likely lead to premature failure. Typically it's considered acceptable to throw a new part into the mix, but not a previously used one. You can avoid early failure by keeping things in order. A good way to do this is to flip a cardboard box upside down and poke 8 holes in the bottom. Make the holes in a straight line and mark what end is the front. As you take the push-rods out, start on one end and remove them in order. As you remove them poke them right side-up into the holes (in the order they came out).

    Installing the rocker arm bar upside down
    There is a flat spot ground into the back of the rocker bar. This flat spot needs to be facing down against the head when you put it back on. Failure to do this will result in over-stressing the rear mount area and will also create too much valve lash. The result is increased wear, decreased performance, and noisy valves. Here's a post where this is explained:
    http://www.toyotavantech.com/forum/s...5800&#post5800

    Removing Injectors from the intake manifold
    If there wasn't any fuel leaks and if the van was running fine before needing the head gasket, then it's safe to assume the injectors are okay. If this is the case I would avoid pulling them out of the manifold. Removing them will take extra time and will create the need for new o-rings, grommets, and insulators. If on the other hand there was a problem with the way it ran, it might be a good idea to pull them and have them cleaned and tested. Most (if not all) major cities have at least one place that can ultrasonically clean injectors then test them. If you have any doubts about your injectors now is an excellent time to have this done (due to the wrap-around split intake manifold it's a major PITA to do the job afterward). If you're chasing a runability problem, then having this done will allow you to eliminate the injectors as a possible cause. Injector service consists of ultrasonically cleaning, and testing. A good shop will test for flow patterns, flow rates, and check to make sure they shut-off completely when powered down. A modern test machine will print out this information for review after the test is complete. More & updated information in the original thread on this subject HERE

    Leaving old seals and/or debris in injector bores
    When reinstalling injectors, a common mistake is to neglect removing all or part of the seals/o-rings from the mounting bores. Make sure the bores are clear of all foreign or old seal material BEFORE installing your injectors. Failure to do so will result in a leak or damage to your fuel rail, injectors, manifold, or a combination of any of these. The parts required for installing injectors will cost around $70. Here are the part numbers and quantities:

    90301-07001 QTY: 4 O-ring for between fuel rail and injector
    90301-23004 QTY: 4 O-ring for between manifold and injector
    23291-73010 QTY: 4 Insulator for manifold side of injector
    90480-13005 QTY: 4 Grommet for rail side of injector
    This article was originally published in forum thread: Other parts to replace while replacing Head Gasket started by rustdogbrown View original post