1992 Landcruiser Oil leak from hole drilled hole in head

[vincentone]

Hello, I am new to this forum and more than likely this problem has been posted previously, but I could not fine it. I have a 1992 Landcruiser 4.0 liter. The small .250" diameter aluminum plug on the right side of the head, (located towards the rear of the head right in front and above #5 spark plug) came out and subsequently I lost near all the engine oil. I replaced the plug and it is still leaking badly from around the plug. I removed the valve cover and it seems the plug does not vent to to this area. Can someone tell me the purpose of this plug and how I can properly seal the oil leak. I am going to need to remove the plug I just put in and try again. The Landcruiser has only 100K miles on it and runs very well and uses no oil, so I would rather not remove the head to fix this leak. Any assistance on this problem is appreciated; or simply direction on where to go to find the proper solution. Thank you.

 

[vincentone]

I notice many have looked at the question but all without response. To be clear, on the right side of the head and in front and above # 5 spark plug, there exists a thru drilled hole of about 0.250" in diameter. Normally this hole is plugged with an aluminum plug. On my Landcruiser (92, 4 liter), this plug has come out and oil pours out when the engine is running. The hole is difficult to get to. I purchased a new plug from Toyota and inserted it by tapping in, but it immediately started leaking. I now have to get the new plug out and determine how to effectively plug this hole. I do not want to pull the head off to perform this seemingly minor job. Has anyone else been confronted with this problem and found a suitable remedy. It would also be interesting to know, just what purpose this hole and aluminum plug is suppose to serve. I understand aluminum used as freeze plugs in water circuits, but not in pressurized oil circuits. I would appreciates comments/thoughts. Thank you.

 

[Shayne]

If you managed to order the part surely it must have a name or even part number that will help people on here seek answers to your question . I just tried to search the interdebt for "landcruiser aluminium head plug" and got millions of results but i quickly worked out none of them were relevent . All i can suggest is you phone Toyota say you bought the part and it doesn't work , should there have been a gasket with it ? .

 

[nivapilot]

Can you get it back out, thread the hole and fit a pressure guage?

 

[vincentone]

Shane and Nivapilot, thanks for the response; the Toyota Part # is 90334-07009 with the description "Plug, Straight". I think I can get it out using a right angle drive Dremel, but it will be near impossible tapping threads in the cast iron head in the very tight work area. I believe I would need to remove the head if I must tap threads. I am still at a loss why Toyota designed it as such and what the purpose of the plug is. The force in pounds on the aluminum plug would be: Force in pounds = [Pressure in psi X (Area of plug squared) X (0.784)] or 70 psi X .04909 = 3.44 pounds of force acting on the plug at a maximum of 70 psi of oil pressure. 3.5 pounds of force acting on a .250" aluminum plug with just an interference fit does not seem like a good idea. I wonder why Toyota did this? I purchased this Landcruiser new in 1992 and just now the plug has become dislodged and I am confronted with plugging the hole back up. Also, the parts diagraham at the Toyota dealer only showed the plug, not a gasket along with. When I inserted the new plug, I tried to clean out the hole and then coated the aluminum plug with blue threadlock thinking that might help. Perhaps I should have simply gone with a metal to metal fit? Thanks for your thoughts and I will appreciate any further comments or suggestions regarding this issue. John

 

[Julian T]

Perhaps a copper washer would help seal?
Or gasket sealant as the picture of the part shows it is threaded so is the hole in the head not already threaded?
Admittedly I have no experience with the petrol 80 engine but looking at my diesel there should be some room to work.

 

[Shayne]

OK the part number let me do a little research and it seems the plug has no real purpose whatsoever . It is there because casting sand must be blown out after the head has been cast . Personally I would get a new plug then clean the hole with alchohol , because oil will obviously prevent the plug from sticking . Then wack the plug in , heat it with a blow torch and let it cool a few times which should make it solid . Then just to be absolutely certain i'd put a blob of 2 part Aradite over the top of it .

 

[vincentone]

Julian, the part I got from Toyota was not threaded and the hole is not threaded. There is some room to work, but probably not enough to rotate a tap. I will of course evaluate for sure, but I can barely get my hand in to place the aluminum plug. Shayne, thanks for researching and your rational for why the hole is there is a good one. I will purchase a couple more plugs and try what you have suggested. Cleaning and drying the hole of all oil is good advice and several heating and cooling cycles makes sense to let the plug expand and contract to make good conformity to the hole. I will probably freeze the plug prior to inserting it and then heat it up and let it cool two or three times. Is 2 part Aradite something like what we call liquid metal? I will look it up. Many thanks to both Julian and Shayne. Hopefully I can remove the currently leaking plug without much difficulty. The part must be ordered and takes a couple days, even here in Houston, Texas, so it is not common. I ask the old time parts manager about it and his reponse was that this was the first time he had ever had a request for one. Shayne, I spend a bit of time down in Exeter, in fact spent all of last week there, probably not that far from you. Any additional thoughts on this matter will be appreciated. Thanks, John

 

[Shayne]

http://en.wikipedia.org/wiki/Core_plug

And yes i would guess liquid metal is a similar thing if its a 2 part epoxy bonding .

 

[Towpack]

Get a new plug and refit it with some core plug sealer. Something like Stag paste or Wurth 250 silicone. You need a sealer that will retain some flexibility due to the expansion of the head/plug so I wouldn't use Araldite or other epoxy. JMO

 

[Shayne]

The aluminium plug will heat and expand far faster than the head , which is likely why plugs are never made of the same metal as the head . Epoxy shouldn't really be needed at all i'd just use it to prevent the plug being pushed out the first time you start the engine before anythings had the chance to warm up .

I would definately not try to glue the plug in with anything at all .

 

[vincentone]

Thanks Towpack and Shayne. I will order a couple plugs tomorrow and give it another try. Saturday, when I inserted the new plug, I did not thoroughly clean the oil from the wall of the hole. I will clean things up better, freeze the plug prior to insertion, insert the plug, let things come to ambient temperature, and then put it through a couple heat cycles and finally seal the the wall on the outside with a two part JB weld, let it set up for a couple hours and then start it up. I will get back on-line and report the results. Thank you all for your input. Additional comments welcome!
John

 

[frank rabbets]

Could you not insert the plug beyond the surface of the head and then hammer over the cylinder head metal surrounding it to make the exit of the hole smaller than the plug? Also check the workshop manual on how to install the plug?

I would degrease with acetone and loctite it in, then hammer over the edge of the hole in absence of workshop manual instructions.

Frank

 

[IRLGW]

Hang on is the hole in the head or in the rocker cover?

 

[vincentone]

IRLGW: The hole is in the head not the rocker cover. Frank, I have a full Toyota Service Manual on the LandCruiser and there is absolutely nothing in it regarding this hole. The problem with the new plug is not that it is pushing out like the first one, but that it is simply leaking oil by the plug. Today I purchased a couple more plugs. I plan on cleaning the hole very good, then inserting the plug after taking it from my frezer. I will let it come down to ambient temperature and then apply a two part epoxy sealer on the outside face of the plug. I hope to be able to drive the plug in far enough so I have a small cavity on the outside to apply the epoxy. The proper fix would be to tap a thread and insert a proper threaded plug, but there is not enough room to perform this task without removing the head. Thanks for your input and if there are more suggestions, please send them my way. Thanks.

 

[OG.]

Sounds to me like an oil gallery blanking plug. When they make the head the gallerys for the oil feeds are drilled after casting. Since a drill can only go in straight lines they need to drill in one direction and then another and it usually results in a hole that requires blanking. I had a gallery plug leak on an old Mini Cooper S and it took months to find. The plug wouldn't come out but was loose enough to leak. Engine running it drbbled oil onto the cooling fan (and all over the engine). Stop the engine and oil pressure would drop, gravity would take over and it would slide back down the well lubricated hole to its proper position.

We found the fix was to push the plug in (the hole is normally stepped or the plug has a step) then tap the centre with a dot punch to spread it wider in the hole (similar idea to core (or frost) plugs).

 

[vincentone]

Your description depicts the issue I have with the Land Cruiser. It is interesting that Toyota does not having anything regarding this in their shop manual. I am going to fix in a manner similiar to what you have described. Thanks foryour description of the root cause of the problem. I believe you are spot on!