Welcome to JustAnswer.com and thank you for your question.
I have not replaced a timing belt on an AQ engine in over 15 years but I do recall that it was not a very difficult job to do (we rarely see or work on AQ engines anymore). The main thing that you must do is to be sure that you align the timing marks on the pullies in relation to the timing marks on the engine block and valve cover.
Do you have a Volvo Penta workshop manual for your AQ145B engine? If not, I could try to post the pictures of the timing belt disassemly/reassembly procedures for you - it may be a bit confusing as I will have to extract just the timing belt removal and installation pictures from the AQ 145B engine teardown/rebuild manual.
Let me know if you would like for me to post the pictures/instructions for you.
Thank you again for your question.
Thanks for the answer....I do have a shop manual that does show one picture of the front of the engine but not very clearly. Any more detail on the marks I'm supposed to align would be appreciated.
No problem, I'll post some pictures of the belt removal and installation process. Bear in mind, you will not have to do all the steps that you may see in the pictures as the photos are from a complete engine teardown and reassembly manual.
Below is the process to compress the tensioner spring and insert a small drill bit into the pressure pin to keep the spring depressed for removal...
Below are the timing marks on the pullies in relation to the marks on the engine block and valve cover (steps 124 - 126 - take note about lining up the marks on the belt with the marks on the pullies in step 126 to check the belt/pulley alignment)...
Below shows the tensioner spring reinstallation process and a general picture of the timing belt and pullies after the belt replacement...
I will also include the ignition/timing specs just in case you dont have them...
Other than the pictures/instructions above, the workshop manual does not include much more info on the timing belt replacement.
I hope that you find this information useful, thanks again for your question.
Just one more thing...
these pics do not explain the marks to be aligned. previous page ?
The second picture down in the post above show the marks on the pullies in relation to the marks on the engine block and valve cover when installing the new timing belt (steps 124,125, and 126). There is no reference to any other marks for the pullies. You should be able to line up the marks on the pullies in relation to the marks on the engine block and valve cover, then install the belt and line up the marks on the timing belt with the marks on the pullies as described in step 126.
I'll be happy to post another picture of the previous page from the timing marks reference page above but all it shows is the installation of the pullies on the camshaft and intermediate shaft. Let me know if you want me to post any other pages from the workshop manual.
Edit: After reading the instructions again, I'm wondering if the term... turn the crankshaft and intermediate shaft "after marking" is the confusion. There is no mention about marking the pullies in any previous instruction, I'm betting the term "after marking" was actually meant to be "at the marking" and is just a translation error (not uncommon on Volvo workshop and parts manuals).
You're welcome! Good luck with your timing belt replacment, I hope it's a smooth and easy job for you.