I was stunned to discover today that (1) the B5244T2 engine in my V70R does not use self adjusting hydraulic tappets and (2) the only means of adjusting valve clearance is to replace the tappet. This parts blow up shows that volvo sells tappets in 0.02mm increments.
So it seems part of the process in rebuilding the head is to assemble the head, measure the clearances of existing tappets, work out the difference between the current clearance and the spec clearance, and order the right size tappet to replace it?!?!?! Why didn't they use hydraulic tappets?! Only reason I can think of is by reducing the weight of the tappet (solid tappet is lighter than hydraulic tappet) the engine can rev a little higher before the valves start floating ... but really, this is a Volvo, not a race car, does it really need to rev an extra 500 RPM?! Can I change out the solid tappets for the Hydraulic ones and accept a lower redline?
Hydraulic tappets in many car makers' engines were dropped for solid tappets. Hydraulic tappets were giving misfire codes in engines using them as direct activating bucket tappets as on the Volvos. The exhaust valve can heat and the stem will grow in length before the tappet can lose oil to contract, especially when starting temp is below 20C. A hydraulic tappet contracts by leaking oil and cold oil is too thick to leak out quickly enough. The quality of the valve seats and of the valves make the solid tappets effectively a non-service item unless the engine is disassembled.
The solid tappets are marked on the underside. They come in .05 mm increments. Volvo has a simple fixture that pushes cam down while clearance is checked. The tool is not necessary and a substitute can be easily fabricated by using a steel strap with holes drilled at appropriate places so the top cover bolts going through strap hold the cam down. IF you use a light touch with feeler gauges, holding cam down by hand is accurate also. Clearance is checked one cylinder at a time on each of the intake and exhaust sides. Find two tappets that are the same size and then place those on top of the two valves for the first cylinder. place cam in journals with lobe "points" facing 180 degrees away from the tappets. Hold cam down and check the clearance. Write the clearance down on a piece of paper, ruled paper is suggested with each cylinder in order and only one record per line. Remove the tappets and place in the next two bores for the next cylinders' valves and repeat for each. Then do the other side of the head with that cam using the same two tappets. The spec is .20 mm intake with .03 tolerance (.17-.23 mm) Cold .40 mm exhaust with .03 tolerance (.37-.43mm) Cold.
Calculate the correct tappet for each location.
Example: using 16.20 tappets for each check, #1 Exh, .33mm, .07 too tight, tappet needs to be smaller than gauge tappet by .06 or .08 16.14 or 16.12 tappet needed. #2 Exh . 44 mm, .04 loose, tappet needs to be larger than gauge tappet by .04 16.24 tappet needed.
Note: clearance too small, tappet gets smaller. Clearance too large, tappet gets larger.
Repeating the calculations should give you a tappet list down the side of each page. Sort the tappets you have and keep in mind your needs list has a tolerance of one tappet larger or smaller even when the needs line has two tappets. The 16.12 and 16.14 on the first example could be 16.10 or 16.14 and be at the tolerance range. The only tolerance limit I avoid is going to .43 mm clearance on exhaust as that can leave a tick in the engine from the clearance as the exhaust valves get longer and the running clearance is not going to remain .43mm but only under load would the valve get hot enough to lengthen and take up the clearance so the .43mm valve might tick at idle. No consequence to having an intake at the .23mm limit if that is what you can get given the tappets on hand.
DO NOT LET MACHINE SHOP GRIND THE SEATS!!!!!!!!!!!!!!!!!!!!!!!!! Two reasons: 1. the seats are hard-faced and grinding goes through the hardening layer too easily, and 2. the valve goes deeper into the seat and could stick up too far for the available tappets from Volvo and cause you to at least to buy a lot of new tappets since it will certain put the needed tappets outside the range consistently used in production. A GREAT machine shop will have tools for measuring valve projection and could grind valve tops to get valves down to the correct projection but this is very time-consuming and expensive and is easily done wrong.
Lapping valves with lapping compound is best.
Hydraulic tappets are expensive and the cam lobe profile is supposed to differ hydraulic to solid. Part numbers for 99 hydraulic and 2000 solid tappet cams for the same application with the same lift are different.
Hydraulic tappets with the proper valve springs have ample ability to rev to the 6500 RPM that these motors are limited to. The solid tappets were not a rev range increasing mod.
whoa, jimmy nice write up but I am having this same problem for a different engine. mine is a 2006 s40 2.5 t5 and I am also rebuilding the head. All that is is left now is to install the solid lifters but I have no idea on the clearance needed for them. Jimmy or anyone if you guys can help here is my engine code B5254T3