I just had my cylinder heads rebuilt they were not leaking but since i needed valve stem seals i just had them cleaned and checked the engine has 181k miles, i nstalled them back in the truck following the shop manual, i used felpro mls head gaskets and new head bolts, cleaned the surface of the block with a scraper and a wire brush and torqued the heads to 83 ft lbs in three steps. The first time i torqued them i used an old torque wrench, as soon as the truck started coolant was leaking at the back of the engine and some in the valley. The next morning i loosened and retorqued one bolt at a time in the right sequence with a brand new crafstman torque wrench and is still leaking even more now in the same spots however there isn't any cross contamination of oil and coolant and no sweet smell or smoke in the exhaust. This is my first time doing a cylinder head so i dont know what to do next. The one thing i noticed is that the machine shop didn't leave a smooth finish in the mating susrfaces of the heads the finish looks like little groves and the head gaskets i used were completely smooth they didnt have the rubber or silicone looking rings around the holes. Any advise on what to do next.

water pump

I checked the water pump where the coolant pipe goes in and it's dry i put a new o ring there before installing the heads. The coolant drippin in the valley is coming out between the block and the heads.

i had this problem after my rebuild. it was the lower intake mating with the heads, because i had my heads resurfaced and they shaved a little off the intake did not want to seal right. after putting a little rtv on the matting surfaces the gasket was able to make the proper seal. i do not know if that is whats going on with you but it is worth looking at.

i looked at that area but is dry the coolant is leaking around the heads where they meet the block

My sr had a leak after replacing head gasket. I used graphite with the white silicone around coolant passages but it turn out to be the coolant crossover tube in the rear of cylinder head. Not sure if your montero has a similar tube that requires loosening to remove the head.

Well i just pulled the heads out again and the only thing i noticed is the head gaskets have two layers one is thin metal and the other one is thicker metal. The thinner side was facing the block i don't know if that makes a difference

Are the oem head gasket multi layer steel?

I tried MLS head gaskets on one of my rebuilds and was disappointed in the results. If the machine shop doesn't get a really smooth finish, the MLS gaskets won't seal. I had a small area near an oil drain hole that showed milling marks - it leaked oil right there. Sometimes the heads are milled smooth, but an uncut block can leak with MLS gaskets due to coolant etching around the coolant passages.

Another leak possibility is at the coolant passages in the lower intake. The intake has a habit of warping up on the ends and sometims a rebuild needs the lower intake trued. The coolant passages on the lower intake can get quite a bit of coolant etching over time - a skim cut helps, as does using Copper gasket spray on the mating surfaces of the heads/lower intake and both sides of the gaskets - 2 coats.

I'm not sure if your engine is a 24v or 12v, but if there is a composite OE gasket that will fit, it will likely fix your problem - if it's leaking because of poor milling and MLS gaskets. If no OE composite gasket is available, see about a FelPro composite set.

I won't mention anything about measuring head bolts and block hole depth...... <img src="/forums/images/graemlins/cyclops.gif" alt="" />

Frank

Thanks for your input Frank, mine were not finished smooth there is definitely milling marks on the surface and i can't find a composite gasket all i find is mls type gaskets i have the 6G74 24 valve soch engine. What can i do now? [img]http://www.4x4wire.com/forums/download.php?Number=1267154[/img]