Please bear with me, I'm decent with mechanics and I can overhaul a simple diesel engine but I don't know a damn thing about gas engines.. Hoping ya'll can offer some advice.




I just bought a '75 HiLux with a stock 20R engine from a friend who has had it for years. They did a rebuild on the engine a couple years back but were short on cash so a couple things got overlooked, one of which was a leaky valve seal. It sat for a couple months before I got and he warned me it would be losing oil but it turns out to be tearing through the stuff on the order of nearly a quart per tank (city driving), which is way more than when he was driving it. So I think I should deal with this. Surprisingly it doesn't smoke a whole lot and I'm not seeing any oil on the ground. The engine runs beautifully, starts with one crank, idles smooth, accelerates well. It's just going through a ton of oil. Anyway I bought a new head gasket and I'm going to see a mechanic friend tomorrow but I'm hoping I can get some help so I don't look like an idiot talking to him.




First off, I'm planning on pulling the head and replacing the gasket because it sounds like that's the only reliable way to do this job. I guess I also need some specialized tools to pull and replace the valve seals? I figure I'll get the mechanic friend to do this, or show me how to do it. Does it seem reasonable to pull the head and bring it to him, or do I need to bring the whole truck? I might add that I have no idea how to do this but I'll have the shop manual in a couple days and I'm assuming that it won't be hard if I just follow the manual? I don't need and really specialized tools do I? I've got a full workshop, just no specific car tools.




The guy who sold me the truck suggested that while I was at it I might as well get the valve seats reground to make sure I get a good seal, since it will be cheap once I've got the head off. Should I do this for every valve, or just the one that's leaking? On that note, should I replace all the seals while I've got the head off, or just the one that's leaking? Seems logical to do 'em all. Anything else that I should think about messing with while the head is off? Like I said the engine runs great. There is a tapping coming
from one of the valves but the guy who sold me the truck said it's always had that so I kind of figure if it ain't broke...

 

Also, I just read some pretty negative stuff about these printoseal gaskets, which I what I got. Are these ok on the 20R's? The stuff I was reading about them failing was mostly on performance/muscle cars...

 

Oh, I found a repair manual download: http://www.retrojdm.com/ScanViewPDF.asp?ScanID=104 and went through that. Jesus there's like 100 steps involving measuring clearances and tolerances with precision tools and all that. Do you guys actually do all that? How much is necessary if you've got an engine that seems to run great but has a leaky valve seal? Am I likely to get away with just having the valves and seats ground and replacing the seals, or do I need to do all this other stuff?

 

You sound like the guy you bought it from, patching is good enough?. If he didn't give receips assume nothings right and check everything, it looks confusing but really isn't that hard. I'm thinking if the valve lash is correct and theres still the clicking you might be right about it being a bad valve. Compression test? If you're burning that much oil it wouldn't shock me if all the valves are loose in the guides (you might need new guides). If once the head is off the valves are tight and only one valve has an issue you might be able to fix just that and seat the valves with compound yourself. Be sure to check head gasket surface for straightness. might need to give it a slight flycut and do same with exhaust manifold, mine had a nice gap in it I had the shop take that down on a big sanding table. Check the intake manifold also for straightness as long as its off, metals lov to warp. If it were me I wouldn't run that motor till you know whats going on inside, if its a bent valve the valve head could break off costing a ton more, U know why I know....Keep us updated and some pics of your truck & motor would be appreciated. Good luck..
ps. You'll have/get all your answers when the head is off...


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Ok, good point. For once maybe I'll take some good advice and do things the right way. I'm going to do a leakdown test before I pull the head, maybe Monday. Then I figure I'll lap the valves myself and put new seals on em all and while I've got it opened up I'll try and check everything. I'll take some photos. I do have a whole spare head pulled off a Celica so that might be useful for parts.
The guy who I got the truck from basically did the bottom end a little over a year ago- bearings, crankshaft, rings, seals, and he got the head shaved. He had pretty decent compression after that, says it was even and he thinks around 160. This is a good friend of mine and a guy who knows his stuff.


A couple questions:
I've seen in some video a trick with zip-ties on the timing chain, do I just jip tie the chain to the sprocket as soon as I get the head off? I'd like to check the timing too, but I don't want to screw it up if it's good now.


I would like to sort out the tapping noise while I'm in there. Going to find my stethoscope and try to figure out what valve it is. Is it likely to be a worn lifter? I'm hoping I could just pull one off of my spare head and replace it, if that's the case.


I'm going to try and fix the windshield wipers tomorrow, does anyone know where I can download a wiring diagram?

 

Pics:

 

U struck GOLD!!! . Looks not so bad but a few hours of fun repairs Good to have a rack.

To get answers u might want to try a new just motor thread "20r problem with...?" or maybe once you get the head off might get better answers to really help. Guess its hard to answer till its apart

I like those years of pick-ups, think there 3rd generation. On this forum they call '84 and before 1st gen but think it should read 1st gen 4x4's. The wiper wiring diagram should be in rear of manual usually? Search, think I posted on that a few weeks ago?