mjtjnj Posted August 19, 2014 Share Posted August 19, 2014 Hi Guys- Long time, no talk. Working on the 87 Laredo. I had a shop rebuilt and assemble my 2.5 a couple of years back, and I had to take the head off because it was blowing smoke, turned out to be a couple bad valve stem seals. Put the head back on myself, but unlike the Chevy v8's I have had apart, there were no dowels, so I used 4 studs in the corners to line up the gasket and head, tightened up in order to specs, and put RTV on the bolt it needed to be on. Immediately, I'm leaking antifreeze, but, not wanting to take the head off, I drove it and put up with it that way, and topped off the coolant. At warm up, and after shut down is when I would see the leaking. It wasn't blowing white smoke. A mechanic friend of mine suggested that the studs in four corners wasn't a very precise way to put the head on, and thought there should be dowels. That brings us to this weekend - I pulled the head off again (don't you love re-doing things, over and over?), and it doesn't look like the block has dowels. So, just so I don't ever have to do this again, what is the best way to get this lined up right? I'm going to take the head to a shop and have them check it out, just to make sure it's not warped or cracked. It was leaking from the driver's side rear corner, I could see the trail down the bellhousing, and the bolt threads were all wet. Getting this head on, on the bench, seems very doable. Reaching up and over the fender, it's another story! Thanks! Tom Link to comment Share on other sites More sharing options...
nitroxsteve Posted August 19, 2014 Share Posted August 19, 2014 If you are using new head bolts cut the heads off a couple old ones and use them as guides. Link to comment Share on other sites More sharing options...
mjtjnj Posted August 19, 2014 Author Share Posted August 19, 2014 That's basically what I did the first time, used studs the same diameter and thread, and dropped the gasket and head down on those. Link to comment Share on other sites More sharing options...
Jeep Driver Posted August 19, 2014 Share Posted August 19, 2014 Based on what I read here, sounds like your head is cracked or warped. Link to comment Share on other sites More sharing options...
mjtjnj Posted August 19, 2014 Author Share Posted August 19, 2014 Could be, but when the block was rebuilt, it was magnafluxed, and didn't leak until I had to pull the head and put it back on. I guess we'll know once I take it to the head shop. From what I'm reading on the internet, these vintage 2.5L's didn't have dowel alignment pins. Link to comment Share on other sites More sharing options...
yxmj Posted August 19, 2014 Share Posted August 19, 2014 If you have the head off.....Get a known "Straight Edge", a carpenters square springs to mind, and check you block and your head....a gap of even half a MM can be cause for concern. On the other hand.....there is a manufacture who makesa a thicker HD gasket for the 2.5....maybe that would help...... . :MJ 1: . Link to comment Share on other sites More sharing options...
Eagle Posted August 19, 2014 Share Posted August 19, 2014 One or two of the head bolts penetrate into the water jacket and have to be sealed. You wrote that you used RTV on the bolt that needs it, but I wonder if RTV is the correct sealer. According to my FSM for the I-4 engine, the head bolt at the left front position (#8 in the FSM illustration) should be sealed with "Loctite Pipe Sealant with Teflon 592 or equivalent." RTV is a gasket sealer, not a thread sealer. Back in the halcyon days of my youth, we used a sticky black Permatex product for the head bolts that penetrated the water jacket, but I don't remember the exact name for the product. Also, the head gasket can only go on one way. Be sure the side marked "TOP" is facing up. Link to comment Share on other sites More sharing options...
mjtjnj Posted August 19, 2014 Author Share Posted August 19, 2014 I'm gonna let the head shop check it out. If it checks out OK, I'll have to be more careful in getting the gasket and head down using the "stud method." Frustrating! Link to comment Share on other sites More sharing options...
mjtjnj Posted August 19, 2014 Author Share Posted August 19, 2014 Thanks, Eagle. The right rear was leaking, but I was following the FSM as to what bolt to coat in sealant. I can't remember what kind I used. I will be sure to use what they call for, or an equivalent. Appreciate it! Link to comment Share on other sites More sharing options...
Eagle Posted August 19, 2014 Share Posted August 19, 2014 I'm gonna let the head shop check it out. If it checks out OK, I'll have to be more careful in getting the gasket and head down using the "stud method." Frustrating! Studs are just as accurate as dowels. The interface of the head to the block, horizontally, is not critical to the thousandth of an inch. You just want to cylinders to line up under the valves and the water and oil passages to line up well enough to allow passage of coolant and oil. Also, pay attention to torque. The bolt with the pipe sealant gets a lower torque than the others. Also, be aware that the torque values for the 1984 thru 1987 engines were different from 1988 and newer. Link to comment Share on other sites More sharing options...
mjtjnj Posted August 19, 2014 Author Share Posted August 19, 2014 I'm gonna let the head shop check it out. If it checks out OK, I'll have to be more careful in getting the gasket and head down using the "stud method." Frustrating! Studs are just as accurate as dowels. The interface of the head to the block, horizontally, is not critical to the thousandth of an inch. You just want to cylinders to line up under the valves and the water and oil passages to line up well enough to allow passage of coolant and oil. Also, pay attention to torque. The bolt with the pipe sealant gets a lower torque than the others. Also, be aware that the torque values for the 1984 thru 1987 engines were different from 1988 and newer. How much lower torque on the sealed bolt? My Comanche is a 1987, but the block came from a YJ from the same era, not sure of the year (87-90). Should I be able to tell the year of the cylinder head from the stamping? I thought I saw an 88 on there, but I'm not sure if it's that simple. Thanks again Tom Link to comment Share on other sites More sharing options...
yxmj Posted August 19, 2014 Share Posted August 19, 2014 Have a look at the secound post down http://www.cherokeeforum.com/f2/cylinder-head-torque-2-5-liter-banger-32293/ This one has a pic http://www.cherokeeforum.com/f2/need-some-torque-specs-130127/ Link to comment Share on other sites More sharing options...
mjtjnj Posted August 19, 2014 Author Share Posted August 19, 2014 Thanks. Gonna go to the shop and make sure the head is OK. Once I find out what year I have, will go from there. Link to comment Share on other sites More sharing options...
mjtjnj Posted August 19, 2014 Author Share Posted August 19, 2014 Ok Just about to take the head to the shop and it looks like its a casting (d12) 408, used from 87-90. Are we sure the torque value change splits from 87-88? Thanks Tom Link to comment Share on other sites More sharing options...
Eagle Posted August 19, 2014 Share Posted August 19, 2014 Ok Just about to take the head to the shop and it looks like its a casting (d12) 408, used from 87-90. Are we sure the torque value change splits from 87-88? Thanks Tom You didn't believe me when I wrote that my info came from the FSM? ETA: I don't understand why the first page is upside down. It's oriented correctly when I view it in Photobucket. Link to comment Share on other sites More sharing options...
Jeep Driver Posted August 19, 2014 Share Posted August 19, 2014 OK, now what do you do when installing a 97 head on an 87 block? LOL Link to comment Share on other sites More sharing options...
Eagle Posted August 19, 2014 Share Posted August 19, 2014 OK, now what do you do when installing a 97 head on an 87 block? The difference is in the head gasket. One gets gasket cement, the other goes on dry. The torque would match the gasket. Link to comment Share on other sites More sharing options...
dasbulliwagen Posted August 19, 2014 Share Posted August 19, 2014 And don't re use head gaskets. One time use only. Link to comment Share on other sites More sharing options...
mjtjnj Posted August 21, 2014 Author Share Posted August 21, 2014 Ok, got the head back from the shop. They did a light milling on it, and said it was good. It cost money, but I wasn't putting the head back on without verification. New bolts on the way from headbolts.com, new Felpro gasket ready to go, I have to get the pipe sealant and put it on this weekend. Here's hoping....now onto the next question thread -- vacuum leaks. Link to comment Share on other sites More sharing options...
ScottJeep Posted August 25, 2014 Share Posted August 25, 2014 The thread sealant to use is Permatex 80633. Use only on the bolt specified by the FSM. Here is a link for a good picture and information. Most GOOD auto part stores should have it. http://www.mscdirect.com/product/details/77847671?src=pla&cid=PLA-Google-PLA+-+Test&CS_003=7867724&CS_010=77847671 Link to comment Share on other sites More sharing options...
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