1992/740/220K/HeadGasketRepair-SomeNittyGritty

rob2volvos · Post by **rob2volvos** » 01 Mar 2010, 09:23

1992 740 Wagon, 220K miles (I think it's a Regina ignition -- there's no ignition coil).
Oil has continued to crop up in my coolant expansion tank. The car has continued to stall when warmed up. It starts very well (always has) -- but makes strange sharp coughing sound on starting. The other day I warmed it up in the driveway and noticed vapor coming from the front of the head gasket, around the water pump. I pulled spark plugs 1 and 2 and both looked weird in the same way. The electrode (ie the actual spark points) were sooty. The ceramic body of the plugs are tinged with a slight yellow/green color, and the there was carbon/oily deposit on the ring area just above the thread.

I concluded the head gasket needed replacement and embarked on the work yesterday. I drained the oil and the cooling fluid successfully without creating an environmental disaster. I WD-40'd the intake and exhaust shield / exhaust manifolds and surprised myself by getting all 16 nuts off in just over an hour.

The intake manifold shows signs of separating from the head without too much persuasion. But the exhaust manifold is stuck fast. I can rock the engine tugging at it -- no sign of separation at the exhaust manifold gasket.
My question is:
Are there any tricks of the trade to get the manifolds away from the cylinder head? I haven't seen any posts on this point and nothing in the manuals ...

Post by **billofdurham** » 01 Mar 2010, 12:01

Tap the manifold lightly with a rubber mallet.

Bill.

tblo760 · Post by **tblo760** » 04 Mar 2010, 11:46

You don't really have to remove the exhaust manifold to replace the head gasket and if it's not leaking why bother trying,leaving it on will also give you somewhere to grip to lift the head.

rob2volvos · Post by **rob2volvos** » 05 Mar 2010, 08:47

Well, I never heard that before, tblo760. Surely it's necessary to detach either there or at a joint further down the exhaust. I (and I would imagine other readers) would be interested to hear more about that.

See what you mean, though about having somewhere to grip the head to get it off. Might not be a bad idea, come to think of it -- given the pain it was to get the manifolds off. Bolts -- no problem. But exhaust joint stuck fast and intake manifold front stud was rusted and also stuck fast. I was PBBlasting (physically and verbally) both manifolds for the nth time by worklight last night and my handy neighbor Peter dropped by to see what the commotion was about. He took one look and off he went to fetch a large pry bar. Using my newly acquired rubber mallet he managed to apply the appropriate combination of force and TLC and we had them off in 5 minutes. Hmmm ....

Removing the 3 belts was also non-trivial. No idea what bolts to slacken on the alternator, water pump and . Just slackened everything in sight and wiggled for an hour or so until I got results. I'm wishing myself luck in advance getting them back on properly. I think I'll need to clean them up (PBBlast?) and think about them. What I really need is a good exploded diagram of each of the alternator, steering pump and whatever I was adjusting on the lower left to get the water pump belt off. And funny I should mention that -- just downloaded a very nice PDF of the alternator bolting layout courtesy of billofdurham. That takes care of the alternator -- excellent! Reminds me of my days building plastic model aeroplanes.

Also no problem removing the 4 bolts on the water pump pulley. Next is the distributor cap. That will be an awkward PITA, I've no doubt. But I'm really not looking forward to fiddling with the timing belt.

Questions:
1) The head gasket directions I have all say that the fan and shroud have to be removed. I have an electric fan mounted right behind the radiator. Is this really necessary for this job? The fan and shroud seem to be well away from the head.
2) When the head is actually off, I'm planning to replace the RPM sensor located at the rear of the block. I noticed that the cable is badly frayed in the aging harness in top center against the firewall (bare metal showing). Is this a good idea/advisable? I understand it's a tricky job which if goes wrong means the transmission needs to be pulled. So should I apply black tape to the cable, hope for the best and adjust the harness a bit?
3) Any special tips on dealing with the timing belt / tensioner? It looks good -- it's about half way through it's life.
4) Does the camshaft have to be detached and removed -- or does that stay with the head when I (hopefully) get it off soon.

Thanks very much for your comments -- very helpful ...

Post by **billofdurham** » 05 Mar 2010, 11:10

Next is the distributor cap. That will be an awkward PITA, I've no doubt.

Why remove it? The distributor will lift off with the cylinder head. However, the cap is not difficult to remove as the retaining screws are captive.

1. That instruction was aimed at the cars fitted with a thermal coupling fan which is attached to the front of the engine and could, very often did, destroy the radiator as the head was lifted off.

2. I have never heard of problems arising from replacing the RPM sensor. When you are that far into the engine replace it as they do fail eventually and yours sounds like it is on borrowed time.

3. Don't let the belt come off the crankshaft pulley while you have the head off. Give it a good inspection for cracks but if it is only half way through its life it should be OK.

4. No!

Keep us informed.

Bill.

rob2volvos · Post by **rob2volvos** » 07 Mar 2010, 16:12

Continuing with the head gasket replacement. I'm following the instructions found here:

http://www.vcoa.org/700-900-faq/Headgas ... Repair.htm

Also, I found the "Step-by-Step Guide to Changing the Timing Belt on the 240/740/940 Volvo, B230 Engine" made available as a PDF download by Frederick Su very useful in getting a better understanding of the timing gear at the front of the engine. He'll be getting my six bucks in due course. Well worth it -- tons of pictures.

Today I got myself a 24mm box socket for my half inch wrench and turned the crankshaft until the notch on the camshaft sprocket lined up with the nub on the rear plate. I marked the belt with whiteout at that point. I used a pipe wrench to squeeze the timing tensioner spring and slipped a 3 mm drill bit in the exposed hole in the tensioner guide rod to keep it in that position. The timing belt slipped off the camshaft pulley quite easily at that point, and I clamped the lower part in position with a 8 inch cable tie pulled tight (so it does not slip off the crankshaft and auxiliary shaft pulleys still concealed by the lower section of the timing belt cover).

Here's my first question:
1) The camshaft end (bearing the timing pulley held on with a (12mm -- or so) nut) extends through the plastic rear plate of the timing cover. How is it then possible to get the cylinder head off cleanly? Does the plastic have to be cut? I tried to remove the camshaft pulley but abandoned that when the camshaft shifted (what was I thinking? I moved it back to the same position, I believe). So what gives? I can't see that the plastic timing cover is detachable without removing the crankshaft pulley.

Then I removed the rocker cover which was no problem. I removed the HT leads from the distributor and labelled the leads and their positions on the distributor with marker and duct tape. The 10 cylinder head bolts exposed, I had a go at getting them off with my smallish socket wrench. Didn't work so I went out again to Sears to get a 14mm socket for my half inch socket wrench. Still didn't work -- couldn't get the torque. Then I had a break and glanced outside and my neighbor Peter (bless that man) had his head under the bonnet. He fetched a 6 foot piece of stout metal plumbers pipe and used that to slip over the socket wrench handle to get the requisite torque to get off the bolts (in the proper order, of course). Good trick. He says he's going to start charging me. But with that trick I have more confidence that I could get the crankshaft nut off if the timing belt ever needs to be changed. I took out the bolts and labelled them (according to the diagram in the first reference above) with duct tape. Didn't need Peter for that.

So now I can shift the cylinder head close to the firewall (as I explained in Question 1) above I don't want to fiddle with the front until I understand what I should be doing with the back section of the plastic timing cover. However, the cylinder head is huge -- a huge chunk of the engine. I'll need an assistant to lift it off (when I can do so cleanly). But:

Question 2)
Once the head is ready to go back on (and the new gasket is in place on the block) -- how do I place this massive chunk of metal back in exactly the right place? If I have to shift/adjust the position I'll surely shear / damage the new head gasket. I had imagined that the head would be guided into place by studs extending from the block. But I just removed the 10 bolts so presumably it's sitting there in freestanding mode.

Question 3)
Given that everything goes well -- what else should I consider replacing while the head is off? Water pump? Is it possible to replace the water pump without getting the head off? If not, I'll do that, too.

Thanks -- What would I do without my next door neighbor?

Post by **billofdurham** » 08 Mar 2010, 12:47

1. You need to unbolt the camshaft sprocket. Firmly wedge the sprocket to stop it turning, slacken and remove the bolt, washer, front plate and sprocket. You should then see the bolts holding the drive belt back plate in place.

2. Put 2 or 4 bolts through the holes in the head to guide you into place and gently lower the head.

3. Very important on these heads is to check for warpage crosswise and lengthwise. This can be done using a steel straight edge or your local machine shop should do it for a small fee. Maximum warpage crosswise is 0.02" (0.5mm) and lengthwise is 0.04" (1.00mm) Head height is 5.752" (146.1mm). If you check it yourself check in more than one place in each direction. If it is warped beyond the limits it can be machined true, if it hasn't already been done.
The water pump can be replaced without removing the head. If there is no sign of weeping leave it alone.

A good next door neighbour is a blessing. I know because I have one. Like yours he steps forward to help without being asked.

Keep us posted, please.

Bill.

rob2volvos · Post by **rob2volvos** » 10 Mar 2010, 10:56

More questions in the meantime:
1) Is there a really good detailed account of how to replace the head gasket on a B230 engine? If there is, I have missed it. The necessity to remove the camshaft timing sprocket has rather taken me by surprise.
2) I called IPD to find a camshaft locking device /and / or camshaft sprocket holding device for the B230 and neither seems to be available. This can't be right, surely?
3) So when I get some time at the weekend, I shall press on by fudging some homemade "camshaft sprocket holding device" (probably consisting of pieces of wood lavishy furnished with duct tape). Is this a reasonable approach?
4) If this goes OK, I can visualize getting the head off, complete with camshaft. However, I am now concerned that I'm going to have trouble ensuring that the timing is not disturbed since the camshaft will shift (particularly if I take it to a shop to have it worked on). I have been fairly careful marking the position of the timing belt, the camshaft sprocket, and I have taken photographs of the engine and camshaft position before slipping off the timing belt. So I think I stand a decent chance of eyeballing the original setup when I reassemble. Is this likely to be good enough to maintain the timing? Is there a good blow-by-blow account of how to check/set the timing accurately on the B230?

Thanks again for your help ....

Post by **billofdurham** » 10 Mar 2010, 12:43

1. The first attachment is from the Haynes 740 manual with their method of replacing the gasket and an ingenious way of holding the camshaft sprocket without a special tool.

740 B230 head gasket.pdf: (1.36 MiB) Downloaded 617 times

The second attachment is from a Volvo publication.

740 Cylinder Head.pdf: (648.96 KiB) Downloaded 524 times

2. Most mechanics would resort to the Haynes method or similar. The special tool will be in a Volvo shop but there is probably little call for it otherwise.

3. See above.

4. If the head does need skimming there should be no reason for the camshaft to move. It will be held in place by the spring loaded tappets (valve lifters). Most machine shops are aware of the problems of a camshaft moving and will, usually, take care to avoid this.

Bill.

rob2volvos · Post by **rob2volvos** » 12 Mar 2010, 14:00

OK -- So I got the head off today -- it's at the shop being resurfaced. I'll make a note of my experiences here, plus add some more questions.
The camshaft sprocket bolt proved very difficult to budge and I wonder if it was over-torqued. I tried various methods (wire, wood chocs) to keep the camshaft steady while I tried to apply the necessary torque to free the cam sprocket bolt. Forget it. Then I tried tapping / hitting the 14mm socket wrench in place on the bolt, and only succeeded in damaging the bolt head. Finally, I reconsulted the volvo sites and decided to use a timing belt clamped in place to steady the cam while I applied the torque. I went to the auto store and bought a new timing belt ($15) and a nice vice grip plier set ($14). Tried the 14 mm socket again -- could not get the required torque. Then I went to Sears and got a 14mm ring wrench. I put that over the cam sprocket bolt, held in place with duct tape, while steadying/grabbing the cam sprocket with the timing belt/vice grip combination -- then whacked the wrench with a hammer and that did it (also the vice grips tore into the timing belt I was using to steady the cam sprocket). However:

1) On reassembly, what torque should this bolt be set to, (and given a torque wrench of course) -- how to apply the requisite torque? Without a cam sprocket holder device I'll have to resort to the timing belt / vice grip /hammer combination. Not looking forward to that.

The timing belt tensioner needed to come off, too. I undid the timing belt tensioner nut and took it off -- and as I did so the tensioner (the thing that has the bearings) jerked to the right. Not sure what I did there. I undid the tensioning pin with a hefty adjustable wrench and the spring and shaft inside it boinged off -- I think I mananged to gather all the pieces. The tensioner then came off the head -- it has a pin that sits in a crevice in the cylinder head. So I have the timing gear in pieces:

2) Where is a good step-by-step account of how to reassemble the timing gear?
3) How do I know whether the tensioner should be replaced?

Then, there were 4 more connection that had to be undone before I was able to get the head off. The main HT lead to the distributor just pulls off. But there are 3 more connections at the base of the cylinder head, under the intake manifold:

4) Right at the back there is a half-inch wide black tube held on with an adjustable hose clamp. Looks like part of the crankcase ventilation system -- but probably isn't -- what is it, actually?

5) Then, at the front there is some kind of sensor with a black plug. Press the top of the plug and pull and it comes off. What is this sensor, actually?

6) In the middle is a third sensor with a copper retaining clip. This was a pain to get off -- partly because I had no idea how to undo it. With a long flat screwdriver and plenty of light I managed to work one side of the retaining clip around the plastic plug. I'm glad I didn't force this because I think I would have broken it had I just pulled on it. Anyway -- what is this sensor, please?

I pulled off the head, wiped it down and took it to the shop -- the 2 sensors at the base of the head, and the plugs I left in place:

7) How do I know whether these sensors should be replaced? They look like they screw into the head a bit like spark plugs do.

The block looks OK -- I can't see any cracks. The old head gasket looks quite good at first glance -- but on closer inspection there is a suspicion of blistering / wear around the channels close to the front cylinder #1, and I think that was my problem. Anyway, I'd like to clean it all up before I reassemble:

How, exactly should I go about preparing the block for the new head gasket?

The piston heads look a bit carbonated:

9) Should I try and get this off? If so, how?

10) Are there any tricks of the trade to ensuring that while I am working on the block I don't deposit the crud down the channels into the engine block?

I have covered it all up with cloth for now. I reckon I am about 30% done. I'll need lots of advice putting humpty back together again -- Thanks ....