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Guest Message by DevFuse

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Doing 2.5L Phase I head gasket job myself...

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58 replies to this topic

#26 Guest_99obw_*

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Posted 26 March 2003 - 02:54 PM

The heads came off without raising the engine. The left side was a bear. I can't see where the gasket(s) failed, but that doesn't surprise me, the leak was relatively subtle. There are a couple of places where it looks like the coating on the gasket is gone.

I used a chain wrench to loosen the crank pulley bolt. The first time I did it, when I did the timing belt, it took 2 of us, with long pipes on the breaker bar and chain wrench.

The tool I made has to be a close second to the dealer tool. I took the broken sprocket to work and indeed the hex is 60mm. The 2 3/8" socket is 60.325mm. If people showed some interest I would weld a few up and sell them, on ebay perhaps.

Regarding your technique 97svx, I have used that technique on manual transmission cars, but this one is auto. I don't think I would loosen the cam sprocket bolts before the belt was removed.


#27 Guest_99obw_*

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Posted 26 March 2003 - 08:56 PM

The heads have been dropped off and will go to the machinist tomorrow. He is going to call me if they exceed .004" out of straight. Hopefully the dealer will have my part.

I actually turned a bolt the other direction tonight, torqueing the new water pump and gasket. :-) The Haynes manual suggested globbing the gasket with sealant, but I decided to go without, just using the OEM gasket. 110 in-lbs.

I removed the oil pump and will reinstall with new o-ring and anerobic sealant tomorrow.

The fact that the old head gasket looks so intact makes it a little harder to believe that the engine will function better when reassembled. The new gasket is four layers instead of three.

The appearance of the cylinders with the expansive water jacket around it just looks like it wants to leak. In my limited experience I have never seen such a design. I assume the design can work, and that this isn't the first production engine to use it.


Edit: The spec in the Haynes manual for straightness of the head is actually 0.002".

#28 Guest_alia176_*

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Posted 27 March 2003 - 09:40 AM

For what it's worth, I was about to do the same thing for my camshaft sprocket (using the huge channelock method). Then I read your post about breaking a tooth so I made up a (crude) tool to hold the sprocket steady while I tighten it wtih the torque wrench. I wonder if using a chainwrench to hold the crankshaft pulley to loosed/tighten method does actually work!

Keep us posted on your adventures!


>I am really pissed at those Haynes manual authors for suggesting such an absurd thing. I never would have tried it if it weren't in that book.

#29 Guest_97svx_*

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Posted 27 March 2003 - 10:45 AM

To loosen and tighten the crank sprocket, I make a tool out of 3/4" wood plank. Drilled two holes for bolts which threaded thorough the plank and then fit through the holes in the sprocket. Drilled a larger hole in the center to get to the bolt with a socket. Then attached a long 2x1" wood handle to the plank. Worked like a charm.


#30 Guest_97svx_*

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Posted 27 March 2003 - 10:50 AM

When you re-install the heads, make sure that you use th proper torquing technique and sequence. Check to see if there are any Service Bulletins which address this issue.

We recently had a discussion on the SVX Network regarding this subject. For wheels, the recommended method was to torque them first in a star pattern to the required value minus 10 ft lbs. Then repeat process to requried value, then repeat it again. Someone mentioned that the SVX has a very complex head torquing procedure, but it certainly does not suffer from a head gasket failure problem.


#31 Guest_WAWalker_*

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Posted 27 March 2003 - 11:26 AM

No, the work you are doing isn't going to change the valve clearance, if you put all the shims back were they came from. The point I'm trying to make is: The valves in a 2.5 DOHC are suposed to be adjusted at 105,000 miles. If that hasn't been done, and your engine has 120,000 miles on it, it needs to be done. Do to normal wear the exhaust valve clearance WILL change in 120k miles. Tight exhaust valves=burnt valves in the future. The dealership here pulls the engine to do a valve adjustment (because they are either to stupid or to lazy to do it in car). I'm geussing 10+ hours. You could check the clearance with the heads off. Then remove the cams to change shims. I don't like to do it this way, but as I said before, it is impossible to do in car without a special tool. Or you could ask the machine shop if they would do it while they have the heads.
The reason I am stressing this is simply because, it is just as important to adjust the valves on a solid lifter engine now as it has always been. But it dosn't get done because people either believe that a new car should run forever without maintenance, or they don't want to spend the $.

#32 Guest_Frag_*

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Posted 27 March 2003 - 12:14 PM

97svx, just so I can profit from your experience, how did you proceed to drill those two holes at the exact locations on the plywood. I'm not to bad at mechanic but not that good at measuring, drawing, etc.
Thanks in advance.

#33 Guest_99obw_*

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Posted 27 March 2003 - 12:37 PM

The machinist called me today and the heads are flat to within 0.001". No machining necessary.

The cams are out of the heads, but I suppose I could put them back in and measure the clearance. Any details on doing this? Does anyone know what a suby dealer will charge for adjusting the 2.5L DOHC valves in the car?

The Haynes manual has head torqueing instructions, but the only diagram shows a 2.2L head. If anyone can post info or a link regarding 2.5L head torqueing that would be great!

#34 Guest_Commuter_*

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Posted 27 March 2003 - 01:45 PM

Do yourself a favour and find out the proper up to date procedure. (WAWalker maybe?). I had heard last year that the procedure was changed somewhere along the way. The scary part though is that there have been reports of leaks etc even with the new procedure, so I don't know what to think. I know that is of no comfort to you, but might as well arm yourself with all the available data.

My understanding is that there is some initial torque down, then backing off, then turning 90 degrees, then another 90 degrees... yada yada. The point is, there isn't actually a "torque" spec at the end of it all. I'd be very curious as to what the final torque ends up being on these bolts. Very curious.

Again... my information is sketchy. Do ensure that what you have in the Haynes manual is up to date.


#35 Guest_JaapH_*

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Posted 27 March 2003 - 05:55 PM

I checked Alldata.com for Service buletins on the headgaskets. Could not find any (does'nt mean there aren't any).
Here's the torque they give for a US 96 OBK 2,5L DOHC:

Cylinder Head Torque Sequence

Note: Apply a coat of engine oil to washers and bolt threads.

1.Tighten all bolts to 29 N.m (3.0 kg-m, 22 ft-lb) in numerical order.

2.Then tighten all bolts to 69 N.m (7.0 kg-m, 51 ft-lb) in numerical order.

3.Back off all bolts by 180° first; back them off by 180° again.

4.Tighten bolts (1) and (2) to 34 N.m (3.5 kg-m, 25 ft-lb).

5.Tighten bolts (3), (4), (5) and (6) to 15 N.m (1.5 kg-m, 11 ft-lb) .

6.Tighten all bolts by 80° to 90° in numerical sequence.

CAUTION: Do not tighten bolts more than 90° .

7.Further tighten all bolts by 80° to 90° in numerical sequence.

CAUTION: Ensure that the total "re-tightening angle" does not exceed 180° .

The bolts are numbered as follows (I only have it for the leftside of the car)

Front up: is number 3
Middle up: is number 1
Rear up : is number 6
Rear down: is number 4
Middle Down: is number 2
Front down: is number 5

I don't know about the right side (US passenger side)

This info might help you. Chilton gives the same.
But I do not know if this is the latest.
Your partsman can prob. help you out.

Appreciate it that you post all your experience. I will do the same job sometime this year.


#36 Guest_99obw_*

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Posted 27 March 2003 - 06:26 PM

I called the dealer and they said valve adjustment is around $400. They said that it was a job that they rarely did. ?? The service department didn't have a price and had to ask a tech. The answer I got seemed unusual to me. They asked me if they were making noise and I said I thought it was piston slap.

I finally put the things I knew together and now I understand why valve adjustment will prevent burnt valves. The stem of the valve will move toward the cam as the valve seat wears. Eventually the pressure the valve puts on the seat when closed will start to decrease. The valve relies on being seated in the head to dissapate heat.

I will take your word for it that the exhaust valves will wear faster. Makes sense. Tonight I will measure the clearances on both heads. That should take a while. The Haynes manual actually has a pretty good section on valve adjustment, with formulas and tables and everything.

I will check that head gasket procedure against Haynes and post later.


#37 Guest_99obw_*

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Posted 27 March 2003 - 07:12 PM


That matches the Haynes manual 2.2L diagram and procedure exactly. That is what I will use unless I obtain a newer procedure. At this point I am not in a super hurry as I have already blown my schedule, so I will probably torque the heads saturday morning. I assume the descriptions that you gave (front middle rear, up down) will work the same way on the right side.

Commuter, maybe a bar type torque wrench could be used to measure the torque. I have the click type. I used a 1/2" drive wratchet and about a 2' pipe to remove the head bolts. Believe it or not I rarely break tools, mostly car parts. :-) I am guessing 80-100 ft-lbs for removal. I don't know how that relates to applied torque.


#38 Guest_Legacy777_*

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Posted 27 March 2003 - 08:57 PM

obw99......you want to try scoobymods or nasioc....as the info may be on there.

scoobymods is pretty good....the engine info should be the same...regardless of what car it's in.

#39 Guest_RodA2003_*

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Posted 27 March 2003 - 09:16 PM

I did this job recently. Here are some suggestions:
1. No need to make a tool for removing the camshaft sprockets - simply remove the valve covers and use a wrench on the hexagon part of the camshafts that is made for this. See www.endwrench.com/pdf/eng...aceF00.pdf for more timing belt info.
2. I ground the valves - it improved the compression from 165 to 175 (car had 180,000miles). Mpg improve 2.5mpg, and it now has much more torque.
3. Adjusting valves afterwards is critical! Contrary to some other advice, I had no problem doing it without the special tool. (BTW it is much less work in general to leave the engine in the car.) I simply measured the clearance holding the camshafts on the clean bearing surfaces and calculated what was needed for 8 thou inlet, 10 thou exhaust. You'll need a micrometer to measure the old shims, as the numbers would have worn off. Buy a bunch of shims from the dealer once you know what you want approximately, and return what you don't use. Double check as you assemble it. If you are careful it should be correct. See www.endwrench.com/pdf/eng...ustF00.pdf for the official guide.
4. Pay special attention to the valve cover gaskets. As mentioned above, install the sprockets first, so you can use the wrench on the camshafts. I jacked up one side of the car at a time to ensure that oil didn't drain onto the cover surfaces. I used high temp silicon sealant in addition to the gaskets. Don't forget to redo the half moon blank plugs with new sealant. I used alcohol to make sure all surfaces are completely oil free.
5. Definitely do the oil pump. This is a common leak point. A new O ring and new sealant is all that is needed.
6. I held the crankshaft pulley with a a piece of 2 in angle steel with 2 high strength bolts at one end to fit into 2 of the 4 holes in the pulley, leaving room for the socket wrench.


#40 Guest_JaapH_*

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Posted 28 March 2003 - 08:42 AM

..... for the archives? Lots of interesting info!


#41 Guest_RodA2003_*

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Posted 28 March 2003 - 01:41 PM

A few things I forgot to mention:
1. Replace the crankshaft seal in the oild pump housing when you have it apart.
2. For both the crankshaft and camshaft seals, I suggest you first lightly smooth off the surface of the shafts with very fine wet and dry paper, 600 or finer. Then smear some oil one before reassembly.
3. If you grind the valves, which I recommend, you can also replace the valve stem seals which will improve the oil consumption. You will need a large G style valve compressor. Many auto shops sell these for up to $100, but I found a $17 one in Sears which was perfectly adequate. They also had a suction cap oscilating tool for about $8. Because of the DOHC head design, you wont be able to use the valve compressor directly on the valve stem. I inserted a simple white PVC water connector to do it: think it was 3/4 female slip to 3/4 male thread adaptor. It's tricky to replace the valve keepers (collets) - one has to use needle nosed pliers and lots of patience. First one took me 45 minutes, later decreased to about 3 minutes. Be extra careful not to let the spring launch a collet into the recesses of your workshop, as happened to me. Didn't find it till weeks later - in the meantime I found some equivalents for free at a local machine shop.
4. Blow out all the oil passages in the head with air. Meticulously clean all debris from the head asemblies.
5. Generously lubricate all the cam and valve contact surfaces with oil before assembly. Make sure that you can turn the camshafts freely by hand after assembly - when the valves are off the cams of course.

#42 Guest_Legacy777_*

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Posted 28 March 2003 - 02:36 PM

yeah.....this is a good archiver.

I'll sticky and archive when it's done.

#43 Guest_WAWalker_*

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Posted 28 March 2003 - 06:42 PM

Head bolt torque procedure is correct.
Easy way to tell how many deg. you are turning the head bolts on the last two steps. Mark the heads of all the bolts at 12 O'clock. After the first 90 deg. make sure they are all at 3 O'clock, final step they should all be a 6.

Make sure the 5 screws holding the backing plate on the oil pump are tight. I take them out and loctite them weather they are loose or not.

You can adjust your valves by removing the cams to replace shims. But the cam caps NEED to be torqued to spec to check clearance. I do them with heads on and torqued, timeing belt on, and don't mess with removing & reinstalling the cams. Simply because the first time I adjusted the valves with heads on the bench, I had to redo most of them after assembly. Don't like to do things twice.

Flat rate for a in car valve adjustment is 3.6hrs. With the right tools the dealer can do it in this time.

#44 Guest_99obw_*

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Posted 28 March 2003 - 08:24 PM

I got up at 4 this morning before work and measured the exhaust valve clearances. I put stuff back where it belonged and torqued it down on the bench. The clearances measured typically 0.007" - 0.008". The heads were a little colder than I would have liked. I ended up needing to buy 5, move 3. The dealer didn't have one of the ones I needed, so I went one size thinner. I will check the clearances in the car and replace any shims that are bad. I also picked up plugs, wires, cam seals, and that blasted sprocket I broke. $300 more spent.

I am glad you told me about loctiting the oil pump bolts. Anything else I should loctite? I have the high strength, high temp stuff. Is that too strong? I am out of the medium, I can get more.


Thanks for the info. I will do the main seal, don't have any 600 grit though, will look for it. I am not going to grind the valves, I don't have time. I will do my best as always to keep things clean. Honestly, I have never seen a cleaner engine. It has had the oil changed every 6 weeks since new. I don't have an air compressor, :-(. I am thinking of using the assembly lube I have and changing the oil at 500 miles, then switching to amsoil. I am also thinking of running the starter with the plug wires disconnected until the oil pressure comes up. I will of course fill the oil filter before installation.


#45 Guest_WAWalker_*

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Posted 29 March 2003 - 06:27 PM

I always loctite the cam and crank bolts too. Get some blue medium strenth for those. They will need to be removed agin somtime. Sounds like you've got everything under control.
Happy wrenching:D

#46 Guest_99obw_*

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Posted 29 March 2003 - 09:24 PM

Today I installed the oil pump, o-ring, main seal, heads and gaskets, right exhaust cam, lifters, shims, and cam seal. I got the blue medium strength loctite and used that on the oil pump bolts. I used the permatex anerobic sealant on the oil pump and I used permatex ultra black on the front cam cap. The heads actually went on pretty easy, and torqueing wasn't bad. I coated the lifters, cam lobes, and cam journals with moly assembly lube before assembly.

Be very careful installing the exhaust cams with the engine in the car so that no lifters drop on the floor. The relatively thick assembly lube makes this easier, holding things in place while the cam is installed.

I did find the 600 grit, and that seamed to remove the little ridges on the cams and crank that the old seals left.

I need to get things wrapped up tomorrow or I will be in the doghouse. :-)


#47 Guest_99obw_*

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Posted 30 March 2003 - 09:48 PM


exhaust manifold, cams, valve covers, oil filler, sprockets, timing belt, idlers, tensioner, back and front covers, cam pos and crank pos sensors, main pulley, ps pump, radiator, hoses, thermostat and cover, not necessarily in that order.

The parts guy gave me the wrong intake gaskets. Phase II gaskets maybe. Another trip to the dealer. |I

It should run tomorrow. :D


#48 Guest_JaapH_*

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Posted 31 March 2003 - 06:54 AM

for giving us all the updates!


#49 Guest_99obw_*

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Posted 01 April 2003 - 07:15 PM

Sorry for the delay. I was too tired to post last night.

Yesterday I installed everything else. That includes but is not limited to; intake, plug wires, air box stuff, alternator, ac comp, belts, fans, overflow, windshield washer tank, and battery.

I removed the bleeder screw and slowly filled it up with coolant. I then cranked it some with the coil pack disconnected to prime the oil system. The oil light didn't go out, but I thought I had cranked enough. After reconnecting the coil, it started and ran well. I didn't fully warm it up and top off the coolant yet. The left rear parking brake has rusted in place or something while sitting in my garage. I brought it into the garage wet. The car won't move. I will free it up and finish topping off the coolant tonight.

I will go back and correct those intake gasket part numbers.

I should drive it to work tomorrow. 100 miles round trip. I will let you all know how it goes.

Thanks for all of your help!


#50 Guest_99obw_*

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Posted 01 April 2003 - 10:01 PM


Well, the rear wheel was locked up because the rear brakes are hosed. You all probably saw that coming. The pads were practically welded to the support/guide thingy by rust. They were coated with neversieze when assembled, but obviously I need to do that more often(done 1 yr, 30k ago). Freeing them resulted in delaminated friction material. I think it has something to do with the record levels of salt used in WNY this year. I have been very unhappy with the non-OEM brake parts. I couldn't find the metal shims and guides when I did the brakes, so they didn't get replaced. The OEM pads are pricey at $75 but worth it IMHO, with all of that stuff included.

Is the rear disc main surface (not e-brake) really turnable? Is it worth doing? They look pretty good.

I need to procure a M6x1.0 thread repair kit to fix the bolt that broke off in the strut tower. Drilling and extraction were unsuccessful.

My only consolation is that I will have lots of new stuff for less than having the dealer do it.


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