Hey all,

Had my timing belt, water pump, etc. replaced due to a super blown up waterpump.....big ouch $$$$ usually do it myself but had to have the rig as its my DD and I didn't have the place or time to do it. Anyways, have a bad (by bad I mean worse than before) oil leak now, suspect it is a pass side cam seal...though it could be my valve covers....have any of you had valve covers really sprout a decent leak? Wondering if anyone has managed to slip the timing belt off/removed the sprockets without taking apart the lower half of the timing system... i.e the crank pulley. Mine has a history of being more than a pain in the ass to remove. I know the guy who did it had to use a lot of heat to get the crank pulley off, I'm sort of guessing he may have torched the crank seal, though again the leak seems like its higher up. Just looking for opinions and encouragement. He's a decent guy so I'm going to call him and ask him what he thinks as well.

 

You can always remove the timing belt from the cam sheaves and leave it on the crank sheave. There is a little piece cast-in to prevent the timing belt from moving on crank sheave while the pulley is still on. I suppose if you really wale on the belt you could get it to move, but even then you'll know you did it because you won't be able to time the cams.

It is VERY easy to install the valve covers in a way to make them leak oil. Usually it's on the back. The FSM specifies sealant (RTV is my choice, but if you're very adept and move quickly, FIPG) in the four places where the gasket covers a join in the castings. Do that badly (forget it, or try to stick it onto an oily surface) and you'll get a leak. So I wouldn't rule out a leaking valve cover gasket.

 

That's good to hear. I think when I can I will re-do the VCs, then check replace/check the cam seals while I have the plenum off. I hope its the VC's. I just did them, but it's very possible I messed it up they have been done 3 times now, but even after my first old school mechanic did them they started leaking a year later. It's a pretty good leak now though...have you really had it come out pretty good due to bad VC's? The other thing is that it only drips onto the ground after the engine has stopped...which makes me think it is from a spinning component. I don't see a lot of oil from right under the main crank, but I suppose it could throw it up that high when it is spinning, you think that's possible? The main thing is the timing of this event - before timing belt job was a slight drip, probably a quart every 1000 miles. After timing belt job it's worse. Is there an oil pump seal in the timing kit? Maybe that was leaking and when replaced forced the leak out of the VC's or cam seals....so much speculation. Guess I won't know until I get to take it apart. BTW I also have the SR5 X Cab, mine's an '88 though.

 

Well sort of good news...I watched the pass side lower corner of the VC and it has a pretty good weep to it at idle; which I bet increases pretty good over a long drive and under pressure. Looks like I will be tackling VC's again and trying to do it right.

 

Something that get's a lot of people who don't know about this in trouble with leaks, is the corners of the half-moon units at the front and rear. You're supposed to use a little bit of sealant, I think FIPR, or whatever Toyota calls it, at the two sides of each half-moon rubber piece. If you don't, it can leak, a lot more than you might think.

Another thing I've found is that if the gasket isn't held into the top of the valve cover as you put it on, it can flop out, and get pinched. I put a little dab of a good thick grease in spots, especially corners and curves, around the channel the gasket rides in. The grease will hold the gasket in place long enough to allow you seat the VC properly.

Last, make certain the gasket is in the channel on the VC properly. The gasket kinda T shaped, with the vertical shaft of the T going into the channel in the valve cover. If you try and cram it in with the crossbar of the T in the channel, it won't sit on the head correctly, and leak like a sieve. It will also prevent the use of the grommets to bolt it down.

Good luck
Pat☺

 

Yeah as I recall I was sort of rushing last time ... never a good idea, especially with the notorious VCs. Going after again this weekend, hoping to do it right, I will be heeding the said tips here. Thanks guys.

 

You can find the correct procedure to install the cylinder head covers (valve covers) on page EG2-80. http://web.archive.org/web/201208130...68cylinder.pdf Note that the bolts are torqued to only 48 in-lbs. Not much, eh? Well, if they are too loose, the cover will leak. If you tighten that steel screw into the aluminum head too tightly, you'll strip it out. I found it worth it to get a 1/4" drive torque wrench just to accurately reach that low torque. Once you have a torque wrench like that, you'll find plenty of uses for it!

 

Yes I am planning on getting a 1/4 torque wrench. You abide by the strict no RTV in the VC channel? I've just read a few other posts where some folks did that after multiple failed attempts the normal way and it helped them. I know if I do that and mess it up, it will be a huge pain to try again. Also, have you replaced the cam plugs? I don't think mine are leaking but I got the gasket kit that comes with them just in case...not sure if I should bother doing it or not. Thanks for the page, that helps a lot.

 

Hmmm. Toyota says use FIPG (or RTV) in just four spots. "Some guy" on the internet slathers it all over the place.

Well, it's your choice. I've had valve covers leak once, because when I applied the 4 spots of RTV I didn't have the metal adequately clean (RTV won't stick to oily surfaces. Then I used paint thinner and a paper towel; brake cleaner might even work better). Mine haven't leaked since.

 

Yeah generally I trust FSM procedure over any slather guy on the internet. Good to hear the procedure worked for you. I'll probably stick to it. That way if it does leak again it won't be a total headache to try again.

 

Alright update, looking for more advice that now goes beyond VC's and oil leaks.

Good news: Found a severed VC gasket on the passenger side and replaced it to spec, including RTV in the corners, 48 inch pounds; no more leak.

Bad news: After putting everything back together I have a code 25, 26. Truck feels like half power - stutters underload, idles at a stutter/lope. My initial thoughts were vacuum leak. I rechecked my vacuum lines, and made sure I had tightened the manifold bolts/nuts to spec. No change after fixing a split vacuum line I did find. I have not checked the others really closely, I will tomorrow, specifically the gas return. Another thought after seeing the codes is the o2 sensor, only because even before I did this VC job I was noticing a little sluggishness when the engine was cold, and I wonder if disconnecting the battery caused the ECU to pick it up as an error after I finished and reconnected. I'm fairly sure my AFM is good, as its not that old and hasn't been a problem. The symptoms feel the way the truck drove when I had the bad o2 sensor, including the intermittent CEL. Before I replaced it the first time, the o2 sensor only acted up in wet weather, otherwise it ran fine and the CEL never came on. But when it was wet, it stuttered and had no power and ran like trash. However, I'm a little puzzled as to why now all of a sudden it runs like this constantly after doing the job, so that is one reason I'm suspicious it could be something else, related to the injectors or fuel. There is a ground on the passenger valve cover that I did not shine up and maybe I should have. I also did jostle the water temp sensor wire (which is included in both codes as a possible problem), though I have replaced that sensor before. I did disconnect all the injectors as to move the wires for cleaning the head surfaces for the VC. I replaced the o2 sensor probably close to 80,000 miles maybe more ago.

My general plan of attack is to order the o2 sensor, in the mean time take the plenum off again, inspect the remaining vacuums, replace the water temp sensor since I have a spare on hand, check the voltage for the injector plugs and cold start, shine up that ground I took apart....looking for general thoughts/advice. Anything else in the injector circuit I should be checking? I'm hoping its just the o2 sensor, but again, it seems like such a drastic change in performance, so it seems like it could be something else. I should also mention it has recent plugs/wires/dist. cap...ignition system hasn't been a problem recently.

Thanks and continue wishing me luck

 

Did you set the idle speed, and check/set the timing after all that? Did you also verify the distributor coil's air gap is correct? That it's resistance is within spec?

I would say it's probably about time to replace again. They only last so long, after all.

Absolutely! That's where the injectors are grounded through after all. So are the plugs. If that ground has a high impedance it can cause all sorts of interesting problems. I am presuming you mean the head-to-firewall ground strap.

I would definitely either check, or just replace, ALL the vacuum lines. If you found one split, there may well be another, or two. They're all the same age, after all. Also, check the corner pieces of the big tube between the AFM and TPS. Those get brittle and develop cracks/leaks over time.

Good luck, and keep us up to date
Pat☺

 

Well, I believe I found my problem. Intake manifold had a blown out section on the 6th intake, which I assume would create a massive vacuum leak, and cause the engine to run really rich. I'm still going to check all the other things I mentioned, since I have the plenum off...again.

I have not checked the distributor coil air gap, or the coil resistance. I think I will just for fun, but the coil is fairly new. Speaking of all these specs, do you guys have a link or source where I can buy/download the FSM for this year? 1988 with the 3vze. The cheesy manual I have is basically worthless, and while I love Yotatech for all of its resources I think its time I have the real deal.

The ground I'm talking about is part of the passenger side injector harness, and is grounded on the head. Is that what you meant?

I noticed some of the PS vacuum lines have a really thick-wall and small diameter - I assume this is because it is vacuum and has to prevent collapse. Is this something you can get at a normal car store? I've only replaced most of the 1/4 soft vacuum.

I also noticed my PCV hose is cracked, so I ordered one of those too. I replaced the grommet/valve. Overall this engine has been incredibly reliable, and still pulls great at 280xxx. Hopefully I found the main issue, which was largely my own neglect and she will be eating dirt again soon. Will keep you posted on my progress. Thanks for the help and advice.

 

Actually, I would think that gasket would cause it to run lean. It's allowing air in that isn't accounted for by the MAF. The ECU is getting information from the MAF that X amount of air is going padt it, into the engine. With the gasket bad like that, there'
s really X+Y amount of air. The ECU is providing the right amount of fuel for X amount of air, so the extra, the Y added in, is leaning it down.
Having said all that, the ECU may be seeing information from the O2 sensor that's telling it it's running way lean, ADD FUEL, so the ECU is over-riching the mixture to compensate. I'm not certain which condition prevails at the moment, but since you're saying it's rich, well, I guess th second is applicable
Is all that about as clear as mud?

No, but that one's critical. Is it a cluster of 4 wires all crimped into a ring terminal, which bolts down where the throttle body bolts onto the intake manifold. If it's the one I'm thinking of, that's the ground for the injectors themselves, so pretty important it's clean, and bolted down well. Be careful messing with it, the wires can break/pull out of the ring terminal.

Actually, I think they're bigger because the barbs they fit onto are larger than regular vacuum ports. Just take one into your auto parts store. They should be able to match it. I've done that myself.

I've seen the FSM for that year, but damned if I recall where. Maybe try your favorite search engine.

Make sure, while you're doing, that you verify the PCV valve only lets air through one direction. I'm almost certain that from bottom (inside valve cover), to top (connected to the hose). If not, get a new one. Very inexpensive, but use OEM, not some auto part store cheapo valve. OEM is THE way to go.
Last but not least, check the front PCV hose. It's a specially formed hose. Small at one end, big at the other. So it's not a hose that they can pull off a reel and cut to fit, you know? Not all that expensive, when you consider how long it's lasted so far

Have fun, man!
Pat☺

 

Well I had quite the emotional roller-coaster.

I think I had 2 different sources of non-metered air. After I replaced the manifold gasket, it still ran like trash. So I inspected the air intake and found a tear in one of the rubber boots...which was not there before I did the VC's so I must have damaged it when I removed it. Replaced that, and ran like a champ, no more CEL. Then, after changing the oil and doing some other puttering, started it up again for a 20 minute test-drive and it ran like trash again....until it warmed up. I drove it 2 and a half hours and it ran totally fine.

Could be o2 sensor going, I didn't replace it as I wanted to avoid cutting up my rusty exhaust until I have to. Any other thoughts? Also seems like it could be electrical/ignition, but I just replaced the cap and rotor, plugs and wires less than 3000 miles ago. I also replaced the coolant temp sensor, pcv hose, and most of my vacuums. I'm not really concerned as it runs great when its warmed up, but it's something I'll have to address. It could have just been the ECU adjusting again perhaps.

Overall, my original goal of stopping the oil leaks was successful. No more big oil puddle under the truck from valve covers. They might seep again overtime, and I think my main front seal is weeping, but that's fine compared to what it was.

Thanks for the support and encouragement.

 

If you do the O2 sensor, make sure to use Denso, or equivalent. Don't use Bosche! They SAY they're compatible, but Bosche is made for European cars, not Japanese.

Have you checked the cold start injector? It could be clogged, or not functioning correctly. Is it's plug in good shape? Is it getting the right voltage at the right time?
You can pull it off the throttle body, put it into a container of some sort, and see what it's pattern and volume look like. All without taking off the fuel line.
Remember, if you remove the fuel line, you'll need new crush washers. ANY time you remove anything with crush washers, you must put new ones in. Never, ever reuse the crush washers. Ever.
Get several crush washers for any job. Chances are you'll need them. Even if you just tighten things a little, then undo them because you forgot to do something, new washers. Also, when you're about to put the very last crush washer in, it WILL leap out of your hand, fall down under the truck, and vanish. Those things are actually malicious that way. If you have spares, you can defeat their plan.

How about the Aux Air valve? Is it opening far enough, and at the right time? Does it close down as the engine warms up?

Ok, shutting up now.
Good luck to you!
Pat☺