1998 V70 Timing belt, cylinder head work 330k miles!

5rivers · Post by **5rivers** » 03 Jun 2015, 06:21

Well, so far I have lapped all 20 valves! And installed them. Problem is there is some leakage - not major - but enough to see water around the valve seats. I have taken all the valves out and will lap them again. My question is should I be trying to achieve a sharp/noticeable edge on the underside of the valve seat to eliminate the seepage? Any links illustrating this would be greatly appreciated!

Post by **Ozark Lee** » 03 Jun 2015, 07:44

My question is should I be trying to achieve a sharp/noticeable edge on the underside of the valve seat to eliminate the seepage?

I use the dye and lap until it is gone on the valve and the seat. The valve and the seat should both have fairly sharp edges on the parts where the dye has ground off.

...Lee

5rivers · Post by **5rivers** » 03 Jun 2015, 11:20

Ok, thanks Lee!!

5rivers · Post by **5rivers** » 20 Jun 2015, 05:30

Back again after a bit of a hiatus...and sanding the bottom of the cylinder head. I am about to begin re-assembling all the parts extracted from the motor area and have a question about the throttle body position sensor. The TBPS was attached to TB on the intake manifold when I removed it from the engine and accidentally left on the TBPS when I began to soak, wash, scrub the intake manifold! I figured it was toast and picked up another the salvage yard. The small bolts that attach the TBPS to the TB were pretty rusted and somehow were misplaced. Does anyone know what size and length these bolts should be?

I have also discovered that one of the 40 or so bolts that keep the camshaft cover in place and attached to the cylinder head has been stripped near the bottom of the bolt inside the cylinder head. Thanks in advance for any suggestions on what to do with this condition.

Appreciate any/all replies!

Post by **erikv11** » 20 Jun 2015, 12:12

The bolts for the TPS are M4 x 0.7, 1 cm long from tip to tip.

The cam cover fastener, is the bolt stripped or the head stripped? If it's the bolt just get another one. If it's the head, I would probably try a chaser tap or even to to get by with turning the bolt in gently and having the other 39 (and the top threads) do the job. But I am not a machinist, maybe someone with those skills will chime in.

Sanding the bottom of the head, yikes that makes me shudder to think about it! I always have the shop do that part and try to not touch it at all.

Post by **Ozark Lee** » 20 Jun 2015, 14:20

The cam cover bolts don't have much torque on them (12 ft lbs) so a Helicoil is more than good enough if the head is stripped and not the bolt.

...Lee

Post by **j-dawg** » 21 Jun 2015, 11:10

A Helicoil in aluminum will be stronger than a tapped thread anyway

5rivers · Post by **5rivers** » 23 Jun 2015, 08:15

Hey, thanks for the replies!
I did find some small bolts to secure the TBPSensor to the throttle body. They were from inside an old non-useable 1996 honda accord distributor!

When I took off the vacuum tree, I noticed significant buildup of rust, etc underneath certain sections of it. I suspect the bolts which have various degrees of stripped threads may have loosened or hardened in place pushing up the vacuum tree and allowing moisture and other gunk to settle. I will see what using a flat file will do. May have to replace the intake manifold if I can't find my tap set.

On the cam cover, the last two or three threads on the bolt in question are stripped, not the head. I do have extra cam cover bolts that I can use.
What is a Helicoil? I have not heard of this, ever!

I sanded the bottom of the cylinder head down to .003" with a few sheets of 120 sandpaper; it took a while to reach that level of flatness (in between days of rain) with a few pieces of level/square wood, a large square, and a feeler gauge. I will attach pics. I experimented on the extra cylinder head I picked up from the salvage yard first before proceeding on to the head from my car.

Is it necessary to use sealant or anti-seize products on the camshaft cover bolts or on the bolts used to attach the manifolds? When I extracted the bolts some had white-colored product on the threads. I had to use a small brass brush to remove most of the material which was made easier after soaking the bolts with WD40. They now screw in with less resistance.

Post by **erikv11** » 23 Jun 2015, 08:19

No sealant or other product on the cam cover bolt threads.

Be sure to use the anaerobic gasket maker to seal the cam cover back down.

5rivers · Post by **5rivers** » 23 Jun 2015, 10:18

Ok, thanks, erikv11

I picked up some red hi-temp RTV silicone instant gasket at harbor freight. Is this acceptable to seal down the cam cover?

1998 V70 Timing belt, cylinder head work 330k miles!

Re: 1998 V70 Timing belt, cylinder head work 330k miles!